AnthonyB

The sockets themselves contain all required safety mechanisms - https://www.fatallyflawed.org.uk/

How easy would you be able to walk into another job? If it's a bad as it sounds & they don't seem to care then it's time to consider 'dropping a dime' to the HSE (as we have process fire risk and H&S issues so sits more in their camp than the fire service) but even with whistle-blower protection if they think it was you then things may get awkward. Is the mixer and it's compressor ATEX as well?

If you are going to add an extra detector, then to be of any use it should be part of the main system, not self contained. If it's a licensed HMO it's worth checking with the Local Authority that they accept an upgraded door in their fitness standards- traditionally upgrading with board as you suggest was an official method in many LA's local guides for many years but times change and it's worth double checking as standards do vary between LAs

Could you please post a picture of the closer?

Ah - Wales! Very different then!

1 - A stair landing with no rooms on/off it does not need a detector to meet The Smoke and Carbon Monoxide Alarm (England) Regulations 2015 (as amended) 2 - You can't usually link Grade D (mains) & Grade F (battery) alarms. However it sounds like the flat already has the legally required detection & under answer 1 does not need the additional one.

An inward opening door cannot, by it's very nature, have a push bar or push pad type fastening (pushing & pulling at the same time is asking for disaster)- but if used by less than 60 persons it need not and a BS EN 179 type A (lever handle operated emergency device) fastening would be appropriate. If you need panic proof escape then the door would need to be rehung. If it opens directly onto the escape stair then unless it is the top floor of the escape it needs to be a fire door (of which metal ones are available)

Firstly you need (it's a legal requirement) a Fire Risk Assessment by a competent specialist who will address this and any other issues. Stairs are, by their very nature, open shafts, but this is not an issue is the stair is a protected route with 30 minute fire resisting construction and 30 minute self closing fire doors with intumescent strips (or depending on a variety of factors possibly even original fire doors with a 25mm rebate). If the offices were fully legally compliant the stairway should already have this protection as well as a suitable fire detection & warning system and emergency lighting. This will give you an overview as well as links to detailed guidance: https://www.london-fire.gov.uk/media/7155/gn_03_lf_format.pdf

If this is on an outer wall it does NOT need to be fixed and fire resisting unless there is an external escape stair within a 1.8m envelope. Furthermore if this is a small block of flats it could form part of the smoke control arrangements if a 'stay put' block (as openable windows are a permitted option for certain small 1991-date blocks and some small-medium legacy pre 1991 blocks)

There is no requirement for the lighting in this area, it seems to be increasingly common to install EL in dwellings, bedrooms, etc despite the guidance not requiring it. Can you borrow a stepladder so you can at least obscure the LED?

If correctly built to the standard of the day, risk assessed & maintained it shouldn't affect existing buildings, but will impact new ones and significant changes to existing ones

Can you readily follow signs such that you will pass through every door, go up or down a stair as appropriate and change direction where not obvious? If so you are fine. Too much signage can be detrimental as they can overload viewers . It all seems a bit excessive, but is a side effect of using a Health & Safety specialist to manage fire safety which is it's own discipline.

No they don't and the OP isn't taking about signs into the building for the fire service or floor signs, etc but standard fire exit signs

They aren't offering to sell you those signs by any chance? Some of it is OTT! How small is the building and is there only 1 exit route? You current set up does sound in line with the risk assessment guidance, which is the legal benchmark.

The way the law has been drafted as it comprises 2 or more dwellings then the external wall needs assessing as part of an FRA but not really much else, although some will interpret this as only applying if there are internal common areas as well - but the law isn't worded way