In contrary to Nick C I would actually recommend Citroëns. But I agree that those with hydropneumatique suspension are probably not the easiest ones. But Citroën also built way simpler cars: The 2CV for example.
In many things the 2CV and most of its derivatives (Dyane, Mehari, Ami 6, Ami 8, etc.: Citroën's A models) are as easy as a car can be — and fun to drive with the soft suspension and the close-to-cabriolet feeling. Actually one of the design principles back in the 1930s was that the car should be so simple that the blacksmith around the corner should be able to do most repairs.
The 2CV's mechanics are easy to understand and simple. No distributor, only two, easily reachable cylinders, no electronics at all (although some third party electronic devices may be better than the original only-electric ones). Some things are unconventional (suspension, ignition) but usually for the simplicity's sake. E.g. the (4-stroke) 2-cylinder boxer engine is rather easier than more complicated than a 4-cyclinder engine. And you can easily remove the whole engine with two persons or one strong person plus a car jack.
Additionally there are also tons of kit cars based on the 2CV due to its simplicity — not only in UK. See e.g. http://www.citrobe.org/kitcars.htm, http://world.citroen1.info/kitcars.htm, http://2cv-kitcar.startkabel.nl/, http://www.2cvkitcarclub.nl/ or http://www.2cvkitcarforum.com/
(Disclaimer: I drive my 2CV for more than the half of my life and of course I'm biased. ;-)