IPAF is valid for five years (unless it's changed recently) and expect to pay £175 - 225 kind of area for a days course/test.
Find a plant / access hire company close to you and ring them up, most of them do training and certs.
Before you parts with your dosh, make sure you know what kind of machinery you're actually going to be using - it's pointless spending a day getting a ticket on carpets and finding a cherry on site. You should be able to do both together but check. And there's no point in learning a 200' mast if all you're going to do is potter around on a 10' vertical platform.