I am sure Bristol have made you well aware of this but beware the 18month time limit from taking your first exam to passing your final one. You unfortunately don't have the luxury of taking it just as slowly as you would like.
I plan to start with Bristol Ground School in the next few months (depending on my work commitments) and aim to get a hour or two at the end of the working day and then full time at weekends. I hope this will allow me to get module 1 done in 6months followed by a bit less for module 2.
Is there an audio CD you could buy or make yourself? Would sound like excellent use of your spare 3hrs on the road!