Do you mean an 'oriel' window? I don't know about pricing, but you can probably contact a couple of suppliers to give you estimates? A quick google and amongst loads of others these came up too. The IQ glass one gives some useful info on sizes I think: https://www.finepoint.glass/product/oriel-windows-london/ https://medium.com/iq-glass-uk/what-to-consider-when-specifying-an-oriel-window-cb39beedce04

How about putting the TV on the wall behind the dining table, that way the sofa can be against the opposite wall which means it faces into the room and there is more space generally. A friend has this and it works well. You could even build shallow storage around it so it’s more like part of the kitchen. Depends on the height of your dining chairs though! Won’t work if they are very tall.

We did get a number of quotes, but they were too expensive for us. So we opted for a large picture window instead. It has worked great and has a very similar look from the inside.

It’s just my opinion but yes I think it would tbh if the leaded glass and rosewood frames were to stay. I think it would probably work if you were to change the glazing and at minimum paint the frames. were you expecting the oriel window to open? I know they’re costly anyway but am sure I read recently it’s a bit of an engineering feat to have an opening oriel window