PIC time - some points to note...
PICUS/P1.S can only be credited with you as PIC on a test with a CAA examiner, eg CPL skills test, LPC etc. Do not take the say so of the simian lifting your money that you can credit that flight as PIC time but naming the passenger as captain. You are not PIC and Bubbles will deny having had the conversation with you when the poor saps at the CAA try to unwind the hash at reckoning time.
Only do this 'structured' time if you are guaranteed - and check the instructor's logbook to confirm - that you have been credited as PIC and captain on these flights.
I would recommend you do not fly with your instructor if you want PIC time. Do not take any preflight planning help - PIC does all this; you are not PIC if he/she offers ANY input to the flight. You may think it sensible to extract as much from your 'passenger' but the CAA say nay.
You will have plenty of time to develop dual time on CPL, ME and IR courses later.
In the meantime, enjoy it.
Patrick