There is a herb called Rue that cats don't like. You have to be careful though as it can cause blisters if it comes into contact with your skin.
Brundog is right they don't like pepper it keeps my garden cat free (Sorry Steph )
Paignton zoo sells Lion poo and elephant poo!

I like the orange peel idea, i might try that tomorrow.

I'm hoping that once i've got it all planted and full of plants that they will leave it alone.

Apparently there's a plant called Rue that cats hate so might plant some of that!

Really?!? I've been looking for an excuse to go to Paignton Zoo for ages! Rich says i've been hundreds of times before and i'm too old!! Finally now I have a reason!!

I'm trying to implement a plan now that kills two cats with one stone - kidding!! I'm trying to utilise my shady corner to grow something that cats don't like.