Hi, I'm newish to commuting too, and new to the forum!
I took ages umming and ahhing over it, then finally my rail card ran out, so the night before I packed my bag and set everything out..then just did it.
I'm loving it so far. Takes me between 45 mins and 1hr to get in, which is about the same time as the train, plus I'm saving train fare (admittedly this is currently being spent on bike bits!).
The strange thing is, is that before I started I was hesitant about London traffic, and some of the roundabouts etc.
I actually find its easy peasy, and the roundabouts are good fun. Basically everything in London is start/stop/start/stop with cars barely moving.
It gets a bit more scary for me nearer to home as the roads are clearer, hence cars are driving faster, which makes it a pain to get into position sometimes. I'll get the hang of it!