I would imagine it'll be a business loan as it would be backed by your business although how easy it is to get a £20K loan without owning the shop or other high value assets I'm not too sure.

Also if you want to pay it off early, that's almost certainly going to add quite a bit to the repayments or hit you with an early settlement penalty, but personally I'd have words with whoever you deal with at the bank and see if they have facilities for this kind of thing plus they have instant access to your financial history.

Maybe even an overdraft facility would be allowed?