You can't find some cotton swabs/Q-Tips and Rubbing Alcohol in the UK (or am I too American to know what a High Street is)?
But yeah, that's what most places recommend, and what I've used before on my SNES carts. Just don't overdo it on the alcohol, and give it ample time to dry. As for alternatives to that though... I know Nintendo once had an official cleaning kit that brought a solution to use. If you can find out what that solution consisted of, you can probably make your own.