You can go to a carpet store, pick out a carpet and have it made into a rug with bound edges. Also, in some carpet stores/furniture stores you can order a rug in a specific size. Worth looking around for that.

Obobble and Suzanne C, thanks for the comments. I think the idea of putting the shower and toilet along the right hand wall is a good idea. Do you think there would be room if I put the vanity unit parallel on the opposite left hand wall, rather than underneath the window? (Sorry I like the idea of having a mirror in front of me rather than the window obobble!) Also what do people think are comfortable dimensions for a spacious walk in shower? If I put the shower in the back right hand corner then I’m not tied so much by the width of the window I think as it won’t jut up next to it? Ie it could be wider that 76.5cm?

I would get a smallish drop-leaf table with two comfortable dining chairs for you and your roommate's eating area. I suggest no barstools - they take up too much real estate. Guests. Ask them to bring a cushion or a folding chair because you don't have enough chairs. I lived in a very tiny place and my guests were happy enough to sit on the floor - 90 minute party, max. Serve VERY good food. Separate the living and dining areas by color/style and/or an area rug for the living room that will compliment your furniture. Decorators siggest that the front legs of living room furniture be placed on the rug if the rug is too small to fit under all of the furniture. If you get a sisal rug, be sure to use a rug pad. Sisal can be like sandpaper on the wood finish of your floors. I would NOT put a rug in the kitchen. Use washable foot fatigue rubber mats instead. Best wishes.

Ah, @Daisy England, I too am a fan of L-shaped corners - but not in the 900x900 variant, which I find far too awkward to access, as the opening is only 4520ish diagonally. But my main kitchen provider does truly wonderful options in 1030x1030 (2x 400 doors, 570w diagonal) and a whopping 1080x1080 (2x 450 doors, diagonal opening of 650 ish). They are a really great & inexpensive way to kit out a corner and keep everything accessible. Or for compact kitchens my German manufacturer does a really great 800x800 L-shaped carousel unit - great for tight spaces! Caldicot Kitchens