Integrated blackout blinds do achieve exactly what it is required. You may encounter a surcharge from your chosen shutter company. You could add a blackout roller blind yourself also. Depending what type of windows you have (particularly sash windows) may be awkward and less elastically aesthetically pleasing than others. Top Tip:- A large louvre/slat will allow more light into a room when open and shall also block out more light when closed. Happy to provide any further guidance or information that you may need. London Interior Shutters

Not fully aware of all your points.. I think there are super slim systems available that you can get that mean you don't need to excavate down as much in the existing floor but not sure how the price would compare. but otherwise generally yes, I think you would need to dig down.. and then it depends on the type of subfloor that is currently there, how far down and what kind of prep you'd need... (it's why we ended up not doing it) and flooring wise we've just discovered... if you're going for Karndean/amtico/LVT they have to have 1day/mm depth of screed that you've just poured before they can pour the latex layer before the LVT! we only found this out really late... and discovered we had a 75mm deep screed... so need to wait 75 days in total.. which overall has delayed it by 2-3 weeks. They can add an accelerant to the screed that reduces the time by I think half. (but apparently is quite expensive) Not sure about other floor types

I would get one involved as soon as possible. I’m not sure what work you’re doing but it helps to have them onboard as early as possible alongside the architect as interior designers are trained and experienced in space planning so can help with layout, door/window placements, kitchen design, electrical/lighting positions, finishes etc etc (interior decorators on the other hand tend to focus on the furnishing of a room although many are qualified in planning by experience). Most will also offer a project management service. I think a number are working remotely atm so it may be that you don’t need a designer local to you? They all have different charging structures and often different levels of service so you can choose what’s affordable. I’d go to the find a pro section on here, maybe make a shortlist of those you like (see 2nd link) and then contact them. A Number of designers may also pass on their trade discount to you so depending on what you need to buy it can be a cost effective process. There are a few stories on Houzz (just search “Interior Designer” in stories) but I’ve just copied the first couple for reference https://www.houzz.co.uk/magazine/ask-a-designer-why-should-i-use-an-interior-designer-stsetivw-vs~26821125 https://www.houzz.co.uk/magazine/ask-a-designer-how-do-i-choose-an-interior-designer-stsetivw-vs~29576346

It depends what sort of electricity tariff you are on. If you also have night storage heaters then you are possibly on an Economy 7 (E7) tariff, with cheaper electricity for seven off-peak hours overnight. Your peak time electricity will generally be slightly more expensive than a regular tariff. It’s worth getting in touch with your supplier, to find out what sort of tariff you are on. If it’s E7, ask when the off-peak hours are (both for GMT and also during BST - some meters switch when the clocks do, others don’t), and set your timer so that immersion heater is on during those off-peak hours. Also make sure that your hot water tank is well insulated.