Hello! It sounds as though the battery has a dead cell. Your other symptoms you listed are typical of low system voltage. When voltage drops too low, the data-bus (communication system) stops functioning. Normally, the charging system puts out 13V+, but if the battery has a dead cell, it can cause the charging system to undercharge and once shut off, will not restart.
Long story short, you will need a new battery, and then to be safe, once its drivable, have the charging system checked, to make sure the failed battery didn't damage the alternator.
Thanks again, I found it this afternoon! Eventually! I'm in the UK so the right hand side over here is the drivers side!
Doesn't look like it's holding a charge so I will buy a new one, will the car need setting up by a BMW dealer when I put the battery in or will it all return to normal do you know?
Thanks again.
Typically, everything will still function and shouldn't require a trip to the dealer.
Don't forget to have the charging system checked once you replace the battery!
Shop Owner/Technician
ASE Certified Master Technician, Owner of a European specialty shop