David - as others have said, try and keep going because you're so close now. I think we all have had days when you start to wonder why you are putting up with it all, I certainly did.
I'm not going to duplicate all that they've said, but one suggestion - go find someone with a PPL to take you flying to remind yourself why you are bothering with all this. Go off for a cuppa at a nice grass airfield, enjoy a still, clear summer evening from 4000 feet or do whatever takes your fancy, because that's what flying is about once you have your PPL. It's not about some @rse of an instructor slagging you because you still cannot do a good glide approach or you've b*ggered up PFLs again (guess what my problem areas were!), but with all the hassle of the PPL it's easy to forget that.
Good luck
