Mr Punter

I can see no reason why the left side would be the principal elevation unless the building is effectively 'side on' to the red dotted line you have drawn and the wall abutting the dotted line is a secondary or flank wall.

You can't move the service head = where the mains cable comes in - yourself. You need to locate it somewhere it will not get damaged or failing that, have it disconnected, then a new service routed later.

I am pleased to note you blamed the kids first. Well done, that is what they are there for. Blocked drain below ground can cause issues. Lift a cover and have a look.

Well @jntabbycat I would be really interested to see the plans and sections for this when they have been worked up. It looks like a fair bit of this will not be timber frame as per your detail but the door and window. The corner post will need to be structural. Be good to show the external paving level, as on the SketchUp it looks level with where you have the sole plate.

One of the firms @Temp linked to above does reclaims http://www.matclad.co.uk/sussex-press-reclaim-230-x-71-x-20mm

Mostly I see the blue pipe just coming into the building, then a stop cock, then copper.

Well that is going to be a heated site meeting with the boss of the firm. Can you get someone experienced who does not take any s**t to accompany you? It looks rough to me but I don't know what an acceptable standard is for this stuff.

Because the land is (I think) the garden of his main sole residence.

Good grief!!!

You can sell the plot(s) with no liability for CGT and pocket the cash.

2 nozzles if you don't use it all at once. Because it is not pre-mixed it keeps OK. They sometimes have a screw cap as well. Yes, grind away!

The 2 part resins set pretty fast. Don't spend more than 5 mins on each fixing hole. Some of the resins use a standard mastic gun, so these may be better for you. Make sure you clean your holes!! Squeeze the resin onto some scrap card until you can see that it is mixing properly in the nozzle. Insert the nozzle deep into the hole and squeeze the trigger as you withdraw, so the hole is about 2/3 full. Turn the studs anticlockwise as you insert them. It is quite satisfying to do if you are fixing something simple.

I get this often. Lots of firms decline to quote for stuff, unless you go through, say, an expensive architect or engineer who the seller / contractor wants to keep in with.

Flow rate is not pressure.

Yes but I don't know if it will solve your problem. (any of them).

Pressure reducing valve?

I used them for a project with about 100 windows and doors - 280m2. They were OK. I would take what they say at face value - they are too busy to want to quote on your project.

I would set the cill at 450mm from FFL so you can use it as a window seat. The window as drawn looks a bit wide and squat.

From your photo it looks possible that you may have asbestos board around the existing window. You can get it checked really cheaply and it will give everyone peace of mind. Some can be removed DIY and some is v. dangerous.

If there is no reason to do it (like boundary or physical geographical feature) then I am not at all keen. Don't waste your money there is no WOW factor in this. The top window is clashing with the roof btw.

I doubt it will increase the valuation much but it will give them confidence that there are not abnormal or unknown costs for these.

@redtop You can have a tank and pump if the rising main is cost prohibitive, but straight off the main is far cheaper and simpler.

I can't see why these things would have any bearing on valuation. More relevant would be quotes / plans for utility connections, surveys, contamination assessments etc.

Where is @pocster when we need him?

Can you remortgage your house with perhaps a buy-to-let? In my experience lenders will not give much, if anything, for a plot with PP. They want to see income to cover the repayments as there is lots of risk if you are highly leveraged. If you have a decent income you can borrow money to buy something worthless as the lender will still get their money back. Having to repossess an asset as the only way to get their money back is not the model they follow. You can obviously sell your house first, but I guess you have a plot in mind and need to act quicker?