Get a container of those blue slug pellets that B&Q/Homebase sell that
contain domestic animal repellant. I find they work a treat, especially if
you put down a nice heavy sprinkling. Costs about £3 for a big bottle.

I think they contain some sort of odour that offends cats. Having said that,
I spotted the animal from two doors along trying to eat some of mine.
Apparently she suffered what my neighbour politely described as "being sick
from both ends". No long term effects though except that she won't come near
my garden anymore.

And I'm slug free too!

Andrew