As has been suggested, it's perfectly do-able, but be prepared to put the rest of your life on hold for a year or so.
I did distance learning with BGS while working full time in London. Did some reading on the train to and from work, then worked for about three hours each evening, Monday to Thursday. Friday night was beer night (to preserve my sanity) and Saturday was a day off to do all the fun things like shopping and housework. Sundays were spent with my head in the books.
By sticking rigidly to that schedule, I managed to complete everything first time in around 13 months. But like I said, forget having a life – my entire year's annual leave was used up on classroom brush-up courses and the exams. It's demanding and requires a fair degree of self-discipline, and some of the stuff will drive you to tears (gyros was my favourite) but with enough effort you will get there in the end.
I can't recommend BGS highly enough by the way.