Flying solo after being briefed and being supervisde by an instructor - log P1.
If flying with an instructor log Dual.
P1/S in your case is only for successful flight tests (like the one you have just done). Well done.
The CAA will not count P1/S time that is no a successful flight test towards total P1 experience claimed for any rating or licence issue. It says so in LASORS.
Why did the CFI have to fly with you dual if you had completed the requirements for a PPL and passed the GST?
Until you have received, checked and signed the PPL it is not valid.
Regards,
DFC