A 944 S2 cab could be the best summer car you ever own, or the worst buy you ever make.
Doing the research on what to look for would be half the battle. For instance, you could ask the seller for the history over the last 5 or 6 years and post it here, along with close-up pics of the bodywork, including inside shots of the sills. You could probably decide on the car from that alone, but an hour with a local indie would not be a bad way to spend a few £s before committing.
The only issue with inspections is that they have to cover themselves. So, they report on every light bulb, the tyre tread, basically all the things you could see yourself. The important S2-specific things like belts and timing chain, brake overhaul, clutch etc. might not even come up on an inspection, yet any one of them would cost you £1K or so.