I would also recommend ETA in West Kingsdown for your inspection. I have used them for a number of years on my E46's and my Zed. They are very knowledgeable, reasonably priced and they take great pride in their work.
Inkey$ had a very good experience at ETA Motorsport near Brands Hatch with his own interlagos hatch back, and Jembo has a guy he uses in Dartford he can give you details of.
Welcome Andi. Late reply to this I know but just commented on ETA for a recent oil service I had there. Highly recommended and will treat your coupe with the respect she deserves. Proper BMW specialists and good price.
http://www.etamotorsport.co.uk/
By the way, as Ruby has already said, very good choice on your flavour of Zed