Birmingham to London 2nd July

a: Don't particularly feel like going to London
b: I'm not that fit
c: It'll be fixed, which is still fairly new to me

Understandable.
Pace won't be mad but route will include several places to drop off.
You'll be fine, quite a few people riding fixed. I'm riding gears though...it is quite a distance and don't think my poorly knee is up to it.

whoah whoah whoah sweet child of mine! ;)

tom, i'm sure there will be times when we are fairly close to a train station, that shouldn't put you off trying. and riding in a group makes everything a lot more manageable. you might surprise yourself.