I logged P1 when solo pre-licence and P1/S for the flight test. Both in the P1 column. I have only had my licence for a couple of weeks and the CAA issued it without any problems. What did your CFI say or suggest when he signed off the log-book before sending to the CAA?
On a similar note - after qualifying PPL, if I have a lesson with an instructor to brush up on or revise any aspect of PPL flying training, do I log this P/UT or P1/S? Is there any difference between that and say, undertaking new training (e.g. night qualification, IMC etc)