I've driven a small number of single seaters including a Formula Palmer Audi car - not sure how similar that would be but, as stated above. there is a high dependancy on aerodynamics, tyre and brake temperature and smoothness of line and input to get the car to work properly. The difficulty is building up the degree of confidence you would require in the number of laps available (once you have exited the pits without stalling ).
The more you can acquaint yourself with track layout, braking points etc before you do it the better.
The best thing is just to enjoy it and hope it's dry.