Yes and yes. I'd strongly suggest you don't buy anything however 'good' the deal until you're in the house.You are stepping quite far away from the original budget 1k£ - 1,5k£.
MA typically refresh ranges about 4-5years apart so the Silver range is next in line and that will be end of this year or next year. No official word when. If it would happen this year then you would start seeing price drops and offers for them. It would be terrible to see new range coming just when you have bought something.
The first thing to nail down is your seating position, the TV position and hence the speaker positions. If you put the TV opposite the bay window with seating in front as is implied in your diagram, then it will be almost impossible to get the speakers in the right place for satisfactory 5.1 sound. I think you should be looking at placing the TV firing down the length of room.