Mr Punter

You would normally have standard gravity drainage with 110mm pipe but this will exit to a pump station - a tank sunk in the ground with 1 or 2 pumps. From there it is in 90mm pressurised pipework until near where it joins to the neighbour, where it will go to gravity again. Whoever did your building regs should be able to do these for you. You pump station supplier should advise on sizing and installation.

If it was me I would consider taking out the suspended floor at the front as well so all is insulated ground bearing. No more rot.

Is this roof, land, percolation or sewage? Most of the calcs for these can be done DIY or from manufacturers.

Agreed with @Thedreamer the top hung ones are a decent compromise. I think they can also be reversed for cleaning.

I think they may have different regs as even single house sites abroad will have a tower crane. Over here the regs make it a bit onerous.

If you need Heras to be dismantled / moved frequently for access etc pay a bit more and get the round topped as the welded top ones just crap themselves.

Break out the concrete. Should not be a huge job. If it is just the area at the back it should only take a day or 2 including disposal. You have spent enough on this that it is not worth cutting corners.

Tesco vouchers used to be good for Pizza Express and ferry crossings back in the olden days

Smack it a bit with a hammer. If it stays on, render over it.

Heating oil! Beware of stuff getting stolen or damaged and bear in mind that any warranty may run from when you take delivery, not when it is commissioned.

If you get a crane in, see if you can get plasterboards loaded out or other bits moved about. Maybe some roof tiles or paving. Your crane firm may suggest someone to act as Appointed Person / Lift Supervisor / Banksman / Slinger, which could be a fair bit cheaper than a Contract Lift. You would still need a couple of people on site to land the loads etc.

On GBF it was often put forward that fuel costs would escalate and insulation costs should be weighed against those inevitable increases. Peak oil and all that.

Need arms like Mr Tickle to open and close the window.

Yes. See https://planningregister.crawley.gov.uk/Planning/Display/CR/2018/0865/PA3 They just did the second floor. It is on the market https://www.rightmove.co.uk/property-for-sale/property-67028349.html Quite odd that they made the flats fairly large. I think they were influenced by the LA planning guidance, but they could have ignored it and had some smaller bedsits.

I quite like the colour of lime in the mortar. I understood it has some 'self healing' properties too. It does make the mortar more expensive and it is nasty to inhale though.

Yes, you can just convert part of the offices. I have seen a scheme like this completed.

The issue here is twofold - skills and money. Was the plan originally to do most of the work yourself? In terms of cost, what is currently on site is probably only 35% of the total cost, so you need to make sure you have funds of the other 65% to complete this before going further. Did the builder draw more money than they were due? Can you get him back, or is that a lost cause?

A bull floated finish should be fine if he is any good. Do not let it dry out too quickly. Cover with plastic sheet.

Those crash decks are really annoying, especially when you have small rooms / corridors to do. I am sure it could be managed another way but the bean bags are not much better. Did you go for beam and block for structural reasons? I have done timber frame over a basement and did a timber floor, just to cut down on a contractor.

Very very impressive. House and plot look great. A shame Ayrshire is north of Watford!

Kitchen unit quality from the low to mid price manufacturers seems fairly uniform. Perhaps just go for a door and handle you like the look of. They all seem to have fairly standard spec for chipboard carcasses, hinges, drawers and legs. You will need to pay a bit more for decent Blum hinges and drawers. Really it is just a row of chipboard boxes chucked on the wall. No magic with any of them. Worktops, lighting, splashbacks, appliances and flooring make at least as much impact as the choice of cupboard brand. Make sure it is fitted neatly.

I just prefer the pump stations with decent sized outlet pipework. They are quieter and far more reliable. Because this is not the only WC, you don't need to mess around with 2 pumps / service contract etc. No plumber will want to see to your broken Saniflo.

If you can, sink a mini pump station in, that would be best. They have a high level alarm. The outgoing pipework is pressurised and often 2" diameter. It connects into the 110mm pipework. Get one that pumps solids, not a macerator. Avoid Saniflo like the plague.

An insulated concrete floor may work much better than timber. You don't need any airflow underneath and there is no risk of rot.

Hi @Mike W and welcome. I am fairly near you and have had a few properties in B & H. Is yours a Victorian terrace with painted render? What are the plans to improve energy performance?