Hi Toby. At the moment I'm looking at doing one end of March, start of April, although I haven't decided just yet which one I'll be doing. Rome looks nice, but is probably a bit too early. Richmond Park Marathon is also a goer, but this is late Spring, so would give me more time to train for. I would prefer an April Marathon though.
That's an impressive amount of weight you have lost. I know it's not the best time to start it, but I'm rationing myself off deserts at the moment......I think it's breaking that sugar addiction......not the best thing to be doing when theres mince pies all around the office!
I think if you carry on at this rate you wont have any trouble getting to 11st. For me its only 1lb a week, which should be doable. I'd like to see some research to see what correlation there is to quicker times and weight loss, and what each lb of weight loss equals in seconds faster.
Good luck on getting those 29 secs off your time.