Code currently isn't working online. However, if you call them up and state you got this leaflet in the 100th issue of the Magazine this month, they'll process an order for you.
Direct Debit details are given, however you are under no obligation whatsoever and can cancel after the third issue has been received.
EDIT: PCG100 does work online.https://imagine.subscribeonline.co.uk/all-titles/games-tm?offer=PCG100
EDIT: Cancellation email, thanks to dodoegg1 - [email protected]