Don't panic... it's easy peasy.
Rear Bearings - 6203-2RS
Carrier Bearing - 6304-2RS
Available in lots of places - Here's one I found on Google ->
http://www.bearingstation.co.uk/Prod...ed/63042RS-SKF
You might even find a local supplier of bearings (if there's on in Carlisle, most places will have one close by)
You will need a long drift/piece of pipe/metal bar etc, take off the carrier and gently tap it out from the other side.
Replacing is easier, use the outside of the old carrier bearing if it is still in one piece and place it against the new one and tap the bearing in (hitting the old one, not the new one!) - simple.
I've never worried about heating, freezing of big presses on my bike bearings, even the headstock isn't too hard to get out. You can replace your wheel bearings on the roadside with the right tools.
If your carrier has gone, I'd be inclined to replace both wheel bearings too, chances are one or both will have taken some wear before the carrier has gone - and for a few quid, it's worth the piece of mind.
It's the same bearing fro the front as it is for the rear. Worth ordering some spares if funds allow.