I can recommend
South West Wheel Repairs in Exeter.
They did a set of D3 fat fives for me a couple of years ago and did a superb job. They're not cheap, but they do proper paint rather than rubbish powder coat. They don't do diamond cutting though.
You can leave the car with them too - they often have a workshop full of high-end German stuff on axle stands. Not sure how long it takes like that though.