<Pops head through door to see whats going on>
Cant offer you to much advice on the training for a sprint and am a bit of a newbie but wish you lots of luck. Having said that I guess you should train about 6-8 times a week 2 swim, 3 bike, 2 run, 1 gym/aerobics/other cross training.
If your cycling to work every day (7 miles, as Cougie said you could tri running once a week) thats a good base of training. On top of that maybe add a couple of swims and a long bike and long run (maybe up to 60mins run and 90mins bike?). Also occasional bricks as WildWill says.
PS. Can I ask a question, im thinking of doing London Tri (Olympic) - did I hear somewhere that its a ballot entry? and if so when do the entries close?