Welcome to Flyertalk and welcome to the BA forum Sara Jane Nisbet, it's good to see you here, welcome on board.

Here is a very detailed thread on the aircraft type involved, I think you have to get to about post 380 before you start to get to real experiences! However there is a more detailed seat map at the start of the thread.

https://www.flyertalk.com/forum/brit...8-onwards.html

Row 4 has got a window at head level, so it's not totally boxed in, but ideally there would be another window before the bulkhead. Personally I would be OK with that seat, but we're all different. There's no one answer, it's really down to your personal preferences.