Old BMWs with 100-150k on the clock and full service history (not necessarily main dealer) 728i from mid 90s is an almost indestructible car with sensible electronics and a fantastic auto gearbox. Will do 35mpg on a long run. Pay about 1500 to 2k, run for a year, maybe 2 and sell for at least 1k. A hardtail mountain bike with wheels and seatpost off will fit in the boot of one and it will shut as well! You can sleep on the rear seat. The sound system is awesome. It's quiet at speed. I once AVERAGED 60mph from Rugby to Arisaig in one.
Big BMWs scare people with servicing costs and stuff but they don't cost any more than equivalent cheaper cars to fix and DON'T GO WRONG AS OFTEN!
They're also fun to drive.
Alternatively, get a Chrysler Grand Voyager from about 10 years ago. Get the manual diesel and enjoy 40mpg and total comfort. All the seats come out of the back and you can turn it into a camper or comfy van. They're hard wearing and reliable. DON'T buy the 3.3 auto!!! Even with LPG fitted.