WeDrove for 3 weeks around the UK last month.We got a standard car and were given a Vauxhall diesel.Great car,lots of boot space which we needed but very economical-got nearly 11 miles to the litre.With the cost of fuel that was appreciated.
Have been hiring cars every Dec/Jan for the last 10 years in the UK, some of these points are universal and some UK centric.
1) Do your research in advance -
http://www.retailmenot.com/view/hertz.com.au (coupons etc)
The place to start is:
Car Hire Coupons & Deals: Avis, Budget, Europcar, Hertz, Thrifty | Car Hire Insider
have a look around it to get the idea. It suggests a couple of 'aggregator sites' that will supposedly find the best deal. I look at both the suggested ones.
I only go with the majors (more response if something goes wrong) as some of the locals seem to have extremes - some reviews are brilliant service etc yet others are the worst thing since the plague.
2) Many UK hire companies are now Private Equity owned (=VULTURES picking over the corpse) so be prepared. Have a small torch (eg: Hertz London suburb pick-up/drop-off in underground garage with only 1 light in 5 actually there (cost cutting). Walked around car and took 8 photos using the torch to highlight any scratches. Not one of the scratches/dents shown on pick-up report so I got that changed - if I had not used my torch I would not have been able to see them. When returning it 12 days later you were directed to a well-lit area (how odd). They immediately started - you've damaged the car. So I pulled out the camera and showed them the photos (one with the damage report included in it) as well as the adjusted original copy of the damage report I had filled out at pick-up and made them sign, write employee number and stamp.
Same happened the next year with Europcar (damage that is) - despite photos and report they then claimed there were more dents/scratches than I had put on the report (and they'd signed, employee number etc). 45 minutes 'discussion' - they try and delay you so you'll buckle as you fear missing your flight - I pointed out that I knew who owned them and they'd better enjoy their last few days of employment. Finally solved but I sent in the info when back in Oz.
Avis - I hired a particular car - in fact it is the only car in its class (at the time) = so I could be certain of luggage capacity. Arrived at LHR - sorry sir we don't have your car but you can have a similar car (different booking category though an intermediate) that had 70% of capacity. I pulled out my copy of the car class description booked (3 large bags 2 medium bags luggage) and the ICAR page as well (so many issues over so many years) and pointed out that the ICAR was only 2 large and 1 medium - so no it is not a similar car. 25 minutes later a "Full size" car was ready that fitted the bags (2 parents, 3 teens in UK/Euope for 5 wks and going skiing) at no cost.
3) If a diesel the fuel usage is less than petrol. If you go up a category then fuel consumption is not that much more and remember the UK is smaller than NZ. Nowhere is far to drive from London. If you've driven Sydney-Melb then you've driven further than just about any like holiday route in the UK. Increasing car category does not make diesel/petrol costs that much more expensive. Did you know - driving a current model petrol Commodore Wagon from Port Macquarie to Sydney (around 110kmh) uses less than 7 litres/100km. Being able to fit in your bags and buy some cheap snacks etc is worth a few dollars a day.
4) Don't take your GPS with you (you then have to buy the maps normally), don't hire one from the Hire Car company but buy one on the internet to pickup when you have the car say from Tesco or one of the electronic chains. Just like here, they are always selling off last years model for a small amount, and you can get lifetime maps with it if you purchase it in the UK (normally). Here is one example from TESCO but not a cheap sell-off one -
Buy TomTom Start 20 Sat Nav, 4.3" LCD Touch Screen with UK Lifetime Maps from our All Sat Navs range - Tesco.com
5) Go retro - buy the AA or equivalent touring directory from the first or second service station you pass once your there. The one I bought 2 years ago cost GBP 1.99, is A3 size closed and A2 when open. Helps give you perspective that a GPS does not. Just like in Australia - they are not building that many new roads so it will last a while but at GBP1.99 does it matter?
6) Premier Inns (except in Airports) normally ALWAYS have free parking. Are like the McDonalds of accommodation and are now the #1 chain used for UK businesses. Even better the room has up to 4 beds and are perennially on special for GBP29 a night (advance non-refundable purchase). Even the Premier Inn in Gatwick Airport on New Year's Eve 2014 (yes I've booked) cost me GBP35 a night. Car hire drop-off is 18m from the door BTW.
7) Just like in Australia, Tesco and other stores have coupons on the shopping dockets for discounts on the fuel per litre - be warned the cost of food in the UK is now less than Australia and you can gain serious weight if you visit any major supermarket early in the morning when all the fresh pastries are being cooked and shelved (5 chocolate croissants for 99p, 4 apples turnovers for GBP1.25, 454gm pork pies for 99p, 6 mini pork pies for 1.25). Real food is cheap too so I am told.
8) Assume that things always go wrong on the final drive to drop off the hire car especially if it coincides with UK rush hours. Aim to be there ridiculously early so you will get bored at the terminal. Two years ago, it was raining, foggy and took 50 minutes to move less than 2km as an accident had happened, cars were over-heating or otherwise breaking down, the emergency vehicles (mainly tow-trucks) could not get through as breaking-down cars were in every lane. Following the leave time rule we sat there knowing we had another 45 minutes before we needed to get concerned (then would be 2.5hrs before departure). We were 5 km from the airport. So plan to not have any stress before your flight home.
Yes the on-the-ball will have noted the booking of Gatwick Terminal Premier Inn for this year's trip and curiously enough we did that last year as well. It can save a day's car hire as well if you're lucky!
9) Get a copy of your CC Travel insurance terms and conditions
TODAY, take it with you, make sure you know the number to call if you need to. There must be no worse a feeling to discover you are not eligible for coverage because you paid cash not CC for your car hire (for example). Ring while still in Australia to ensure your understanding of the terms is correct. Ask for the person you speak to for their full name and employee ID#, write down the date and time and ideally ask for them to mail something out to you or make a note on your CC contact file about your enquiry. Take a copy of the T&Cs with you.
If you prepare for the worst then you can only get a pleasant surprise!
Oh, and enjoy your holiday...