There are lots of ways that this could be laid out. I think you have made a good start but for me there are some things you have done that seem unusual but might still be right for your circumstances but finding out those goes beyond a post like this. For instance the main reception is a really impressive sized room and moving the stairs here is a shame when there are other places they could go. It’s seems odd that both living spaces should be open to the kitchen. If the spare bedroom downstairs has big doors to the hall it’s not very private for overnight guests and getting to the WC is also not very private- perhaps this room should be at the back? If you were to extend perhaps it would be better to keep the parking at the side and the possibility of a garage by extending out the back instead. And it seems an unusual choice not to have an ensuite to the upstairs master bedroom. Using a concept planner or designer is the obvious thing to do for this kind of project. You can just pay for a few inexpensive hours of work and you could end up with ideas that you would have never considered but make the inevitable spend on renovations more certain to deliver what you need and want.

externally if you would like to go ahead with cladding i suggest to use at least 30mm graphite insulation board first then membrane out and timber buttens across and cladding over. that would give you a much more better efficiency in a longer therm for a low cost. at a same time government would provide a scheme for insulating a houses in a next couple of weeks and covering 80% of your cost up to 5000£. thats more likely covering all of your built up and you just need to pay for a cladding byself. back to the subject regards of a rendering. new type of renders as like silicon is the best product i ever use. you get colour warranty on them and you could jetwash all the walls as many times as you want without to scretch them or without to pell off. nowadays we are doing many external insulation projects on line with the extensions and give a new look and better efficiency for our finished products

Don’t just concentrate on the cost of the works. You also need to remember the cost of hidden extras like skips, extra costs of not having a functional kitchen (regular and frequent takeaways are very expensive!), tea for the workers (more than you think), and the insanely time consuming and brain-frying issue of decor and soft furnishings. Also, factor in a contingency of at least 50%, because you’ll definitely go over budget and building costs will increase during the works because supply is definitely not keeping up with demand. We had an awfully long wait to get our ration of 5 bags of cement…

You will need a good builder with a favourite structural engineer. The walls don’t hold much up but they do strengthen the outside walls. Personally I think the front door on the side dates the property and moving it and using the garage as an entrance will make your home feel much bigger and create a space for better bathrooms where the old front door was.