What shall I use the room for?

Walk in wardrobe/ dressing room??

I have a similar dilemma (though for different reasons) in my house. It used to be a junk room and then we cleared it and now its just staring at me with just a bookshelf. My issue is that ive got an old house and i cant create that snug type room as it will need heating a lot beforehand due to it having an external wall x