You should try the commercial landlords first as they carn't give them away at present, because after six months they have to pay full rates on an empty building.
I know a bed place that got a 28k unit at 11k a years. You certainly want a good rent free period.
Problem with councils as I've found is they have no interest in a rent free period, they progress very slowly, the application form was 22 pages long and wait for it you are limted the want a guarentour if you defalt on the rent and a payment to check your credit file.
Steer clear of evanseasyspace, they charge the rent, plus there own electric and gas charges, which are upto 50% more, then they charge a climate change levy (what is this I don't know) then finaley a 10% admin fee + VAT.
Also you want a rent agreement that you can get out of not a full term lease which are a ballache.
Regards
Graham