Initially I took about 2 years to get 10 hrs flying done, due to weather/work/lethargy etc etc and then eventually did the whole thing in 4 weeks in California.
Even if you don't do it outside the UK I would still recommend doing it over a short period, full time. It saves money and is an enjoyable and rewarding experience.
In your case if it takes you 2.5 years part time or 2.5 year + 4 weeks including a 2.5 year gap full time I know which one I would prefer to do.
Do as "28th July" says and keep asking on PPrune for PPL's to take you up as a passenger. I have done plenty of flights alone for the sake of staying current and hour building and would have preferred to have had an interested passenger along side.