I visited Specialist Cars BMW in Stevenage a number of times before I purchased a car. At no point did I feel pressured and was left to roam, sometimes with children jumping in and out of different cars. Upstairs is where they keep many of their M cars and even there I felt no pressure.
I eventually bought a new BMW F90 M5 and I was treated with a level of care and attention that was right for me. As in no pressure. I was provided with answers to all of my questions and given helpful tips and advice. The setting is relaxed and the coffee is good too.
Based on my experience, a highly recommended place to buy a BMW.