Hi HPSC,
You'll get far more knowledgable posts than mine, having a ground total of 1 hour in the logbook so far, but here goes!!!
You don't need any provisional licence, just pay up and go for your first lesson, but if you are going for the "full" PPL as opposed to the NPPL, you will eventually need a CAA Medical before you can pass.
Not REQUIRED to start learning, but best to know beforehand if you've got something that would stop you getting a licence before you spend lots of time and money. Your training school will be able to let you know of a local GP who can do the check for you. If you don't pass the medical don't give up hope for private flying as the NPPL may well still be available to you.
Hope that helps, and the very best of luck when you do start.
