I take my car to the place in Tower Hill which happens to be right next to where I live. Took my E46 there for 5 years and now my E93.
I used the Bromley Car Wash next to Bromley North station, they used to do a pretty decent job too but annoyingly they would change the playlist on my stereo to Tupac and leave the volume pretty loud when I picked it up later in the day!
I'm new. Go easy on me