Remember also that, if it's a private category C of A aircraft, then you must comply with ANO Art 130 if money is going to change hands. There is an exemption for an aircraft you own yourself or one that is jointly owned by you and up to 19 others but it still involves getting a maintenance certificate from a licensed engineer. For permit aircraft ANO Art 9A may provide a similar exemption with the permission of the CAA.
BEagle - I stand corrected - it's 12 months for revalidation by experience but it's probably worth emphasising that the 12 month period in which the 12 hours etc must be is ALWAYS from the expiry date NOT backwards from the date you are getting the licence signed if you want the revalidation to run from the expiry date.