Took me a shade under a year to complete. If I may offer a suggestion, if you can commute on the train to work then do so. If it takes longer then so much the better. I did nearly all my reading on the train to/from work and just handled the progress tests at the weekend. I found it very easy to concentrate, except when I overheard the occasional mobile phone conversation about sim checks!
I reckon about 8-10 hrs a week is needed.