She may do well to have the boiler serviced - the engineer will be able to tell if there's a room thermostat and advise on having one fitted. They are often placed in the hallway.
I once moved into a previously unoccupied flat that had no room stat - the effect was that with the central heating on there was no effective control - the boiler continued to run and heat the property until turned off manually.
In your daughter's place - without a room stat - Thermostatic Radiator Valves (TRVs) will provide some control if she has them.
The slow to heat radiators may be caused by a problem not associated with the missing thermostat.
I think this boiler was last made in December 1995.
Peccavi
February 2010