I am now posting about what the venue was like as an Aspie. The journey wasn't too bad - there wasn't too many people on the train and tube when I went (different story coming home). I found the venue easily as I'd been there once before. Usually when I have been somewhere once and know I am going again, I remember the route. The talk was at the Sir John Balcombe pub in Marylebone. There is the pub upstairs with the function room downstairs. There was music going on in the pub but it wasn't too loud and you couldn't hear it from down below. There wasn't any music downstairs. It had twinkling lights on, so if you don't like lights then it wasn't for you. It was fine for me. No noise, low lights. The seats were spread about, so people talking didn't get too much for me.
All in all, except the travelling by bus, train and tube, the venue was OK for me as an Aspie. I will go there again.