Hi,
I'm 3 years in to racing and having been driving a midget in the MGCC midget/Sprite series, but have now got a formula ford and will be racing with classic formula ford with HSCC this year also. So, I can perhaps relate to your question quite well.
My suggestion would be that the FF is not ideal for a first time racer. With a dog hewland box, and much more adjustable set up, they are not as easy to gel with straight off as the midget. The other thing is that the FF series generally do not allow wet specific tyres so when it rains, they really are a handful and again, not ideal for a newbie.
I agree with the suggestions above to avoid the moderns (mx-5, caterhams and definitely the radicals)....but then this is the historic racers area and we are biased
. Midgets and other similar classics are relatively forgiving in race trim - think of a normal classic but much faster. Yes, you need to adjust to driving north of 4000rpm but most other things are similar such as a synchromesh gearbox. I can recommend the midget/sprites as a good way to get experience without spending a fortune. CSCC are good similarly and with swinging sixties, you clearly have more choice of vehicles. If you like the more period-authentic racing (so those running 'close to' FIA appendix K), the Equipe series are good and have good grids. These cars are generally dearer though.
Just my thoughts and happy to be PM'd if you'd like to discuss as I was in a similar position a few years' back.