If considering wood you could get unfinished wood installed. Companies such as Wood Floor Accessories are a great supplier. Having it finished on site means a finish can be picked that works for your home. Each home has variables such as pets, different traffic and the owners desire to maintain the flooring or aversion to maintenance. Having wood finished on site has advantages. You can pick the highest quality product that works for your budget. The range of finishes available is quite wide. A professional company will try to understand your home and recommend the appropriate finish. They will also understand how easily the finish was can be renovated in the future. Amtico is an extremely robust product but being plastic, is just plastic flooring. It has its place, as does wood. In areas that have plenty of light surfaces, scratches show very easily on Amtico, Karndean etc. The manufacturers push a polishing maintenance product on consumers. However, this needs to be stripped and reapplied on a regular basis.

We are coming to the end of a house renovation and we had wet UFH installed in all our rooms. It is a bungalow however, it is very unusual property with rooms below the bungalow so it is like a house in some respects. We have a mixture of solid floors and suspended timber floors and couldnt have a screeded system because of the weight. We had an ESP overlay board system installed and have found it to be very effective. Ours is run off an ASHP so I cannot tell you how it would work off gas central heating. Our UFH is on 24/7 controlled by thermostats in each room/area. We did install internal wall insulation on all of the external walls and window reveals and voids beneath the floorboards where possible and my understanding is that this is key to efficient and cost effective UFH.

If you made outer wall then its okay to build window on the side, your neighbor privacy will be maintained and you can get the sunlight needed, I would advise to move the garage to the front so it can be accessible for a car from the main road, you can still have direct path to the garden from the front if you move the enterance to the right and just put a fence, if it were me here's the layout i will do, it'll give more space for closet, bigger bath, utility room, and additional storage unit, so basically move the wall to the left and focus buildng that side, the previous garage will become the new master bedroom with en-suite

oh old post to practice, the obvious choice is first floor extention but this only if the ground foundation on the back supports for this floor. Its mirroring the outer wall of the ground floor so enough area, there also alternative option of cantilever steel beams or concrete floor slab for first floor side extention though maybe need additional permit . Bedroom 3 will slightly Bigger than original, Plan A Plan B - Very Narrow Hallway Plan C - With Cantilever