@joncooper27
We had a lift installed 2 years ago (wife is a full-time wheelchair user), our 2nd lift (not in the same house). The first lift several years ago was a through-floor platform lift, quite industrial/clinical looking. The cost then was I think around £4000 to go one floor up. As
@Terry - Somerset said, putting a lift inside a house loses most of the utility of one room per floor unless you have very large rooms, so we lost a dining room and small bedroom. Whilst the lift installation includes a strong-enough-to-walk-on cover over the hole in the first floor so you can't fall down the hole (it is lifted up by the platform lift when it comes up from the ground floor) you can't put any furniture within 300mm of the lift footprint on either floor.
In our latest house we didn't have any room inside to put a lift so we had a lift shaft and lobbies added. The house has three storeys so this was not cheap. This time we went for a cabin lift. Total cost >£70k!! The lift itself was £25k, basically ~£8k per floor. But the house and location are what we wanted and the room sizes are perfect so worth the spend.
A through-floor lift goes through the floor (!!) and doesn't have a full cabin (no full-height walls and no ceiling). You cut a hole in the ground-floor ceiling/first-floor floor, fix some steel uprights, and the lift attaches to those. On the lower-priced ones you can see and touch the walls, more expensive ones have a shaft/tube. On all through-the-floor lifts you have to keep the button pressed to keep the lift moving. These tend to use an Archimedes screw to drive the lift up and down.
A cabin lift is what you get in many shops and hotels, but built for the domestic market. A full cabin with walls, floor and ceiling, and you don't have to keep the button pressed as you can't touch the building walls so can't get hands and other bits of anatomy trapped! These are typically about £8k per floor and up. Ours is hydraulic, you can get archimedes, belt drives and pneumatic. There is even a cabin lift that fits externally to the building without a shaft.
https://www.levellifts.co.uk/products/shaftless-cabin-lift/ . Cabin lifts tend to require a pit, although this can be as little as 50mm.
HTH
Steve