Concerns about tree roots could be from the neighbours or due to a TPO. We’ve been through this recently and have designed our extension to avoid the entire tree protection area (based on an arboricultural report-a requirement for us even to apply for planning). Despite that we have planning conditions on storage of building supplies (not near any trees), not being able to change ground levels (eg around patio areas) and being required to dig manually, not use diggers for fear of damage to roots. An arboricultural consultant should be able to advise on where and how you can build in relation to the tree, and then you would need the Council to accept the consultant's opinion. I assume the vendors must have had an opinion to plot the protection area? Also my understanding is that TPO legislation overrides permitted development legislation. As we've several TPOs, we’ve got to know the local council tree officers, but it’s the best approach as there can be heavy fines if you get it wrong.

@Jonathan I don't dislike it either. Agree that additions of various things would make it more appealing and a heater would certainly make it nice and cozy. The side fencing will also be changed soon which will smarten it up. It's just a case of our needs at the moment with the little ones. Definitely agree with the path also. I'm not keen on where it is at the moment. Just have to decide on the shape.

I don’t have much to add apart from be honest with yourselves about how you live and what you need - will you really use a cinema room? We had a similar extension and left a small courtyard area as 123 suggested - this was mainly because we also left a side path to get into the back garden. If I’m honest with myself, my own middle room is wasted - our front room and middle rooms had been knocked through years before we bought the house. The door into the front room was blocked up and we only have the door into the middle room. It means the room is pretty much a thoroughfare but with a couple of pieces of nice furniture. We simply don’t really use that half of the room. It looks nice, and it makes the room feel spacious though... we have a gorgeous desk in their that we inherited and we have tried to make it a study space, but in reality we don’t use it for that. If I was to start again, I’ve seen a few examples on here where the middle room has been turned into a lively big utility and also a pantry space for the kitchen. I actually think for a family, that’s far more useful!

It is a challenging layout for sure. First try: Dining definitely near the garden, space for 4, but also for 6 when needed. No boot/mudroom, kept as much open as I could. Imagine a tiled floor throughout and a nice big doormat to zone off the area. Bench next to backdoor, then app.35cm deep units for shoes and whatnot. Shower room (shower pan is 80x80cm), washing machine in hallway cupboard. Kitchen with extra deep worktop on cooking side. Lots of tall units on the opposite wall, perhaps some low ones with upper to store toaster and coffee machine. Then towards the left a play area and some shelving/baskets so they can tidy up while you are cooking.