If I understand correctly, they are paying you to sit at home and do nothing for two months, then when you start work again after two months you will need to work off that "debt" as unpaid extra hours.
What happens if you get a new job during or after that two months - will you have to pay some kind of compensation? They may say you have to pay some kind of compensation but are they telling the truth - is it legally enforceable?
What happens if they lay you off at any future time after the two months - do they write off your "debt" or are you liable in some way?
You should carefully examine these issues before before deciding anything I think.
Depending on the points above I would say that if you have a job/contract just now stick with it. I think the next few years are going to be extremely tough for anyone out of work, especially unskilled manual workers.
No point learning to be a plumber or similar building related trade since that sector of the economy is in serious decline right now.
There are loads of courses you can do, subject to being able to pay for them, that are not tied to the academic September to July routine. Beware though - even in the best of times employers don't like employing paper experts with no real life experience.
Just a suggestion - do you know anyone, or could you hassle someone, to take you under their wing as a trainee, (low paid), during your two months off. That might lead to something permanent.
I am going against the trend in this thread but I think you should stay put, but use the time to to think about, and plan, and organize what you want to do with the rest of your life work-wise. Getting a lump sum of cash and getting out of a tedious job is tempting. On the other hand getting a two month paid break is tempting.
As someone else said - since they are paying you to stay at home it doesn't sound like your current job/contract is totally secure in the medium term