I have just finished both modules with Alex Whittingham at Bristol. Having started in Feb this year I needed 2 weeks in March for Brush up and then 4 days in April for Exams. It was the same in July and August with 2 weeks brush up followed by 4 days Exams. Alex is very good and the feedback is as good as any you will see anywhere else. Beware of infighting amongst the various schools - it is all Bull.... The feedback is all much the same, but some of the answers do vary. I don't think that is really significant. I passed all subjects first time and one or two with only a mark or two to spare. It was a fairly stressful few months and required some time away from wife an 4 children to allow focus and study.
With only 4 weeks annual holiday I don't see how you will get enough time off to complete all exams in one year. However if you are in no hurry then go for the 2 year option. None of it is Rocket science, but does require application and discipline - forget about largering it up for while. The amount it will cost you will probably be enough to focus the Brain cells.
Can't say enough about Bristol Ground School. I have heard a few bad mouth comments from other agency students, but Bristol got me through all subjects first time for ATPLA and I am a military chopper pilot and most of this was all new totally new to me although I have a pretty good handle on the Maths and that helps.
Good luck