Thanks mate, I'll grab some pics ASAP but to clarify the issue, steam has a setting to adjust the UI scaling when you're using a TV since you are sitting further away. That works fine in big picture, the interface is nice and big and readable.
I'm playing in 4k but over 3 metres. When you launch the steam overlay in game the UI is suddenly tiny and not full screen; the text is unreadable and I'd expect it to look the same scale as out of game. No idea what to adjust to fix.
Likewise when I launch the steam keyboard in game, it's tiny. I can interact with it but I can't get it to type, but that's a separate issue lol