I started cycling on my own about 14 months ago, then joined a club about 6 months later and have done 4 club 10 mile TTs. I had been timing myself over various routes, gradually getting faster, trying some gym work, adding some intervals - but nothing prepared me for the intensity of the TTs. I didn't do quite as well as I hoped/expected, but it has spurred me on to work harder over the winter and I'll be back next year. I also hope to find my way into some longer ones ( I have this idea a 25 would suit me better) and some open ones next year. So go for it - but be prepared for it being tough. A club with a confined series is definitely the way to go in my opinion.