BMW Stratstone advertise
1st service Oil service £149
2nd service Inspection 1 £249
3rd Service Oil service £149
4th service Inspection 2 £349
(all 6 cyl engines) Probably plus VAT, but you do get free coffee while you wait.
Personally I think you car is too old (not an insult at all - mine is older) to take to BMW, so unless you have some warrantly that requires it would skip them. The price they charge Vs a local specialist makes it not worth it. Long gone is the old argument that a full dealer history will hold resale values.
My local guy will do Oil service for £50. I don't need to pay £70/hour to tell me my indicators flash and that my washer bottle was already full, etc.