If Really stuck for a workshop you can trust and don't mind dabbling yourself you could try an online support option such as

https://shop.myautoaid.com/

Using the diagnostic tool you can get assistance with the particular results you read over the internet

https://shop.myautoaid.com/diagnostic-tool/pro/bmw/ gives you an idea of how deep they can diagnose on BMW stuff but obviously with the Mog it's primarily the power train side of things.

It could be worth contacting Morgan and ask what diagnostics they would recommend

Mark - No Longer driving
Archie the Old English Sheep Mog...........
2010 Roadster 3.0 V6 (S3) wink