You are in the enviable position of having the whole space designed to suit you and your lifestyle ! And the bonus is the windows and doors can be put where needed ! Every designers dream project !! If you want to ‘do this yourself’, feel free to look at some of our uploaded past projects to maybe give you some ideas - alternatively why not consider booking yourself in for a design consultation - either with someone like us - who DON’T sell anything other than design, but that means you can shop around and compare like for like with the plan that was designed specifically for you - or book with someone who will design for free - but make money on what ever they sell you. Although they don’t usually let you keep the design - so less easy to compare like for like with other shops. Either way -it’s an opportunity to get something amazing that will work for you !! Enjoy it !

I wouldn't bother with a bench - not very comfortable. I agree with others - get as much storage as possible, leaving enough room for a play area on the floor, at least one comfy chair for supervising adult, and a child sized table. To make a loooong storage unit attractive, I found the stepped Trofast system good (from Ikea). When you put two units together it creates an interesting 'top-line' where you can store and display toys and teddies that don't lend themselves to being kept in boxes. Also a good surface for a CD/music player and lamp. Since you have a long wall, you might like to put a standard unit in between the stepped units, or to increase the storage volume you could put units beneath the stepped units (increasing the overall furniture height). There are also wall units in the Trofast range. These are shallower, but accept the same drawers, just in a different orientation. Are you familiar with the Trofast system? you can get Trofast drawers and bins/boxes of varying sizes. The extra deep bins (see white bins in last photo) are great for costumes, balls of various shapes and a big wooden train collection. Medium drawers (see pink bins in first photo) are great for all sorts. Ordinary drawers (see white drawers in lower photo) are great for paper, face paints, crafting bits, sorting lego, miscellaneous small things that kids always seem to accumulate (whistles, bubble mixture, plastic dinosaurs). The bins/drawers are cheap so can be changed arranged as needs change. Various colours avail; and the pine wood option can be easily painted. Although it's not as attractive as some systems, e.g. the bookcases in your photo, it is much more practical having drawers of varying sizes. You can improve the look by adding wall art decal / stickers / transfers. Trofast is also very sturdy system. Ours has lasted years and is still going strong. We even used it for makeshift kitchen storage for 6 + months when renovating our backroom. It stored all sorts of plates, cutlery, bowls, glasses, dry goods, and we could pile the top-line with microwave, cereal packets etc. It has now returned to the playroom. i.e. very versatile for family life. The above photo shows a unit that could go between the stepped unit. A bit like your bench idea. You could add a suitable facing piece, and you can also create 'changing station' for any little ones. The last photo shows a unit that could go under the stepped units (also three columns wide), provided you secure them safely together. Also available in white. If you google "Trofast Ikea hacks", you'll get loads of ideas. Including ways to include a child's desk in the long run. e.g.

Sorry, my camera hadn’t been enabled at time of posting- can you see them now on my new post?

I don't know what everyone likes stylewise or colours but I quite like the houses on the wall in the first pic on the wall where your sofa is. The kids could update the characters in the Windows using decals when they grow out of a phase. It's only paint so easy to paint over when they're teenagers. The rest of the walls i'd do in a scrubbable paint. Where the radiator is i'd add a table like pic 2 but with the shelves underneath the table in pic 3 for craft storage (maybe make it deep enough for a games console in the future). I'd also add cheap shelves above for art and pencil storage etc with bins etc. The desk could be raised when they grow but also used as a tv stand when they're older. The eames chairs are kids one, they're easy to keep clean and quite cheap at £25 (seat height is 32cm) for when they grow out of them. I'd add a rug in the middle and the beanbag by the bookcase. You could add a "once upon a time" or a "read" decal over the bookcase And maybe star bunting or Pom poms over the eaves to cosy up the reading area. l'd add clothes pegs on the cupboard door for their dress up stuff plus a couple of toy bags for lightweight bits. I'd keep the rest of the room free for play (although the existing drawers could be handy) and when they're older add a sofa for tv, PlayStation etc. What type of lights do you have ATM?