how hard or easy is it to change the drivers side front inner wheel arch liner
and does any body know how much they cost from the dealer

It's easy, just undoing some screws and a bolt, it's made much easier by removing the wheel.

Cost is £40 from dealer, part number is 46784585

i dont think fitting any size alloys to your head let alone 17's is going to be aesthetically pleasing

Lol, damn go my money spending plans!