gijoe - are you the owner of the C152? If not, how exactly do you 'have the use of it'? I understand that it's OK to test someone in an aircraft which they own, but anyone else must use one which has a Public Transport (Passenger) C of A? The C152 you're referring to does, I presume?
Also, make sure that it has the level of equipment needed for your test as explained in the PPL Skill Test 'Guidance for Aplicants' Standards Document....