Useful websites:
List of all the main governing bodies websites below, broken into two divisions, road racing (massed start bunch racing) and time trials (individual timed races, riders set off at minute intervals).
Road racing:
North West Road Race & Criterium League:
http://www.cdnw.org/
British Cycling (Road racing):
http://www.britishcycling.org.uk
LVRC:
http://www.lvrc.org/
Time trialling:
RTTC (Time trials):
http://www.cyclingtimetrials.org.uk/
L&L SPOCO:
http://www.walliscycles.com/spoco/spoco.html
Entry forms can be downloaded from the RTTC and BC website's. Once you've done a few events list your times on the form, even if you didn't get a result, for first few events just fill in the event and personal details. Send it to the event organiser with a cheque. The details of the races are listed in the CTT handbook for time trials, you can order one here: http://www.rttc.org.uk/ you can view more early season events there as well. You can get a CTT handbook from Geoff Smiths cycles as well.