In reply to BStar:
Thanks for all the replies guys.
I know they are small, but that is kind of why I want one. I want to replace my non-economical car with an economical one, then I saw that you can get the belrlingo/doblo/kangoo car that do about 50mpg. Being vertically challenged at 5'6" the length doesn't really bother me, but thanks for the good advise on making sure I don't get skewered.
I thought that the back seats would get checked on an MOT, so if they were removed it may change the MOT somehow. Knowing when a car with junk in it (with removed seats) becomes un-insurable or becomes a camper van is another thing I am unsure on.
I looked at getting the van version of each of these vehicles, having pre-cut windows and an inside trim rather than bare metal swung it the way of getting the car version. I guess it might make insuring and modifying it easier though.