Good morning Gsa,
Most of us PPL(H) pilots started with a trial, and the term "Hooked" took on its real meaning, consider the following:-
If you are endowed with enough cash to give lumps up front, then as others have said pay by credit card, or have some sort of written undertaking from the Owner or Director of the outfit, in this day and age of high credit problems "NO ONE " is immune(See RBS PLc, Last week).
But having now got your agrrement or Credit Card cover, why not not do more training and flying per month, one problem with you only doing so many hours per month (5hrs, I think you wrote) is that you will need to spend time re-hashing part of what you have already learnt , why go over already trod ground when if you can get the time sorted out properly you should be able to double that. Looking back on my training I took two leassons per week at least and got my License at 40 hours, only at the end of my training with the Cfi prior to my flight test did we go over the many aspects of the envelope of the sylabus that I myself just wanted to tighten up on, for me it worked, why not try it this way?
Peter R-B
Vfr