Sounds like the correct way to get ripped off, stipulating how the required finish should be achieved. That's for the decorator to advise on after inspection.
Too many variables to quote for without seeing job. However typically I would look at three/four days work (7 hrs/day on site) assuming that it is in pretty good order to start with.
It will need:
Wash down walls, ceiling and woodwork with sugar soap, and rinse.
Sand, fill and sand any blemishes in walls and wood.
Minimum of two coats of emulsion ceilings and walls.
Prime where necessary then undercoat wood (16 hours drying time) and then gloss.
Bear in mind that painting doors, door and window frames can be very time consuming if there are lots of detailed mouldings and are done properly, and there is drying time between coats.
Labour about £130 - 150 per day, materials emulsion £40, paint £20, disposables £20.
Best bet is to get a recommendation and several quotes and get them to explain exactly what they are going to do.
A relative of mine had four rooms 'decorated' for £400 - i.e. one coat of white emulsion on ceilings and walls - no wash down and no woodwork painted! She got what she paid for.
All my work comes from recommendation - I have never needed to advertise.
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