My advice would be to look through the MSA Blue Book -
http://www.msauk.org/site/cms/conten...p?article=1122. Especially sections K & S (but not only these. Then you'll start to see the requirements for clothing and car prep etc.
205 always a good fun and competitive car. I used a Saxo VTS and the Pug 106 GTi is also competitive - ideally the 106 over the Saxo even though they are much the same. Clio Cups of various ages are very rapid and also in a managable price band now too.