Castle Combe is great fun, and I would say well suited to a Mk1 MR2. No really long straights where the lack of top speed hampers. Try it, you'll enjoy it.
Ive track day'd my MR2 at Goodwood, but have always used my Seat Ibiza cupra 2.0 16v at Castle Combe.
I'm there tomorrow as passenger in my mates e36 M3 evo as a shake down for a Nurburgring/Spa trip later in the year.