Hey there, thanks for the replies. Now before I make my final decision I have uploaded the dimensions of the other room. Its more rectangular but smaller.
The door at the back, opposite the window is the entrance to the room. The brown door to the right of the window is a cupboard.
This leaves me with two questions:
1) Which of the two rooms would make a better mixing room and why (size , acoustics etc)
2) How would you go about setting up room 2 for mixing (listening position, treatment etc)