Laptab are the renowned company in these parts, but I have used A1 in Bilston, and they did a cracking job. Recommended to me by an Integrale owner who's wheels they had done. I saw the before and after pics, and that was enough to persuade me.
Many places advertise as wheel 'refurbishers/renovators' but do check what they actually do. They should be able to repair the wheel properly (weld in alloy where required) and if they have a good reputation will also tell you when it wouldn't be safe to repair.