Get one with a Honda engine. My Dad still has a 400 series, some of which had the Honda, some Rover - He has a Rover engine and it's had to be rebuilt a few years back or some major work. Not sure if that applies to other models.
Don't do it lad, it's a slippery slope. Before you know it, you'll be buying elasticated slacks out of the Radio Times and having your Sunday lunch at a garden centre.
I've got an s-reg MGF. Nice little car. 120 hp, and I've done a few things with it, for example I installed a wider throttle body and a body stiffness kit.
The K-series Rover engine in it is a decent motor. A bit finnicky at times, but reliable nonetheless.
Many Fs have now reached the end of their lifespan and are going to the breaker's, but that also means spares for your own car can be had nearly on every street corner. And if you're not picky about mileage, you can get an early F with 60k-plus on the odometer for 1000 quid and under.