Oh.

I take it they're the same thing then. Whoops.
'cooling mat' didn't have the word fan in it anywhere, so I assumed it was something else. Now that I think about it of course, I've no idea what method the 'cooling mat' would use if not a fan! Just bought one anyway, £9.
If you search for "USB Fan" on eBay, I got the one that is clear plastic with three fans and blue neon lights. Lots of people are selling what look like the same thing, not sure who I got it from though.
It is cheap and the wires look like they will fall apart but they haven't so far. It does the trick and is well worth the money for anyone using a laptop on a desk or other hard surface on a regular basis. Even if you're not having over heating issues I'd recommend one, it will keep it cool and it gives a good typing angle.
Possibly the best £8 I ever spent.