Depends on what level you want to race and what class, club races there are normaly very few restrictions, and correct me if I'm wrong but its too late to register for nationals.
Lots of info is available at the BRCA site, and individual clubs will normaly state restrictions on regional events, ie no LiPo's etc
http://www.brca.org/
But I bet you could have lots of fun beating folks who are running new gear in your old car with Nicads, ( my cars fine but me the driver seems to be the week point )
Best advise nip into your local club and chat to as many people as possible, thats what I did and they were all very helpful