Quote The Fold Studios:
I am self-empployed and run a small recording studio. Am I in trouble if I don't have PAT testing on all my appliances?
Just to reinforce the point, technically no, but you you'd be foolish not to have formal PAT or some similar alternative plan in place.
If anyone gets hurt of if you have a claim on your insurance one of the first things you'll be asked for is evidence of an appropriate and competent system to check and maintain your equipment.
As has been said, the major and most important part of the PAT is the visual inspection which you can easily do yourself. Provided you keep good records of what equipment was tested and when, that should suffice.
Personally, I'd recommend that you take a PAT course at your local college. It only takes a few weeks, it really isn't rocket science, and it doesn't cost that much to do. That way you'll be qualified to test your own gear, and you can also test that of all your mates to earn a few sheckles in the process....
Technical Editor, Sound On Sound