Tom Tom new memory card problem

need some help guys.ive just d/l the new GB map and cos its so big i need a new sd card.ok got one and thought i could just back up my original card and then transfer to new one then put the maps on there but it wont let me restore my old stuff on the new card it says its for another tom tom??do i have to format it and how do i do that?wouldnt mind but i have some favorites on there that i really need and i cant transfer them.

also after d/l the new GB map it turns out i have most of the moajor roads of western europe too on there lol.wish it would have said its nice but i dont want them as it takes so long now to get my routes!!!!!!!