I've done some googling and looking through GZ but can't find much.

We are travelling into Spain for a few days, then to the UK (or is it just the K now?), then to Austria for a few days.

Can I set up the sim to do all that? How expensive will it be?

It's probably just going to be a little data, but I don't want to fart about with wifi hotspots.

Device is an iPad Air 2.