Welcome to the CCCUK forum - and a 'guarded' congrats for purchasing a C3......'guarded' as your "huge rust problem underneath" doesn't really give us much of an indication as to what the problem is? - is it chassis - is it the 'birdcage' - is it to do with the 'trailing arms' ?
Irrespective of what the problem is.........finding someone to restore the car can be a 'cans of worms'. If you look back through the pages on our forum one specific 'so called' restorer convinced four or five of our members to hand over their cars for major works and over a period of a few years or so and was 'farming' their cars for parts. He ended-up going bust, hid all the members cars (and others) elsewhere with the police and detective agencies searching for the restorer and the cars. And it isn't an isolated incident - there are many cases of these things happening, irrespective of what the marque.
I'm sure our members on here will be able to come-up with suggestions, whether it will be in Sussex is another matter but a full restoration on a C3 or any Vette is likely to take many months or longer and run the risk of costing you more than the car is worth.
Suggest you spend you £45, join the club, look to attend your local regional meeting and go in to more detail here about your car.
