We repair those here in the US, but I'm not sure if anyone is Europe is repairing them. It's actually our main business.
If you replace the control unit, you run a near-certain risk of the new part's failing soon, too.
But if you want to try, you can find UK part suppliers and authorized servicers via http://www.sharp.co.uk
In my professional opinion, people should not work on a microwave unless they are fully informed and aware of the deadly hazards and necessary precautions.
One can find such information and very specific in our safety and disassermbly text files at http://www.microwavedisplay.com
You can find safety and disassembly text files (as well as a text file which helps in diagnosing and repairing door switch problems) at http://www.microwavedisplay.com
William Miller † MicrowaveDisplay.com, March 2007
