It took me a little under 18months; as i was working shift work at the time I had to go part time to be able to fit the study in;
I found that you need to build in revision time into your study for the very reason you describe; if you're also only going to study at the weekends, you are IMHO going to make life very difficult for yourself;
Whilst the brush up courses are great and they give you the info you need you still have to go to them prepared with some knowledge; EGCC may be under estimating the work required to a new starter; The study is not difficult but there is a lot of info to absorb;
Good luck;