If you are qualified and current its P1.
Dont let an instructors nick your hours just because he is sat beside you. Agree before hand if the flight is instructional purposes or not.
No where in LASORS does it state that a club or insurance requirements can dictate how hours are logged in line with any 28 day requirement, etc.
LASORS states that an instructor can only log PIC for "all flight time during which he acts as an instructor in an aeroplane or supervises SPIC flying". Well you arent a student and if he isnt instructing you because you have already agreed its a club requirement not a licence requirement.....