[skidlids]

In your position I would pick my circuits/race meetings and enter both classes as the 2nd class usually works out quite cheap. Always plan on doing both 500 races and the first 600 race and if your having a good day do the 2nd 600 race as well, if your not put the 600 back in the van after the first race and save it for a better day.
A good day with the Extra tracktime could help build your confidence more quickly.
This is from someone that has done 6 races in one day on two different bikes and even done 12 races over a weekend.

Kev