I think your list is too long. You should only be asking questions that would cause you either to not make an offer or to make a significantly different offer. I find it really odd that people look at small details on houses, as if there's a row of identical houses all for sale that just differ by those little details.
I'd also aim for yes/no questions as some of the dates stuff would be a pain to answer.
My thoughts:
1.Please confirm the construction date of the property
What difference does this make?
2.Does the property have any current or historical movement: subsidence or heave?
Ok
3.Any history of damp in the property? (rising or penetrating?)
Ok
4.Is the property covered by building insurance? Current cost, any claims, has cover ever been refused?
What difference does this make? You can't use their insurance. Just get an online quote.
5.When was the extension constructed? Can the vendors confirm that the appropriate planning permission was granted? Is there any guarantee remaining on the work?
Ok
6.Roof: is it the original pitched roof & slates? When was maintenance last conducted? Any history of leaks?
Most roofs don't need maintenance.
7.Flat roof: when was the flat roof on extension fitted/replaced (any guarantee remaining?)
Seems ok to me
8.It appears that the original windows have been replaced: when & any guarantee remaining?
Are you really going to decide whether to buy a house based on how much is left on a window guarantee?
9.It appears that the upper floor ceilings have been replaced/replastered, but the living room & kitchen retain original Lathe & Plaster ceilings: can the vendors please confirm the status
Are you really going to decide on a house based on this?
10.Loft: is there a water tank in loft? Is there any loft storage?
Systems/condition
Ok
11.HW/CH: confirm that hot water & central heating is operating well, age of system & when last time system serviced
Is this really a deciding factor?
12.Electrics: I have not seen the fuse box: location & age? When were electrics installed/last checked?
People don't normally get their electrics checked. Unless they are really old, I wouldn't expect this to be a deciding factor.
13.Where are stopcock & cut off for gas supply, & gas/electric meters
Is this really going to make you not buy a house?
Misc
14.Any neighbour complaints/disputes?
Ok
15.Any history of burglary/trespass?
Ok
16.Confirm chain free status & what is the vendors preferred timing if sale agreed?
Ok