Still bigger than my two story one bedroom. Her house did go back a fair way in length.
I know what I would do. Rent it out rather than sell it. I presume it must be worth at least £2500 in rent a month being in the area it is in London. If she is planning on moving to the countryside where propertys although expensive out this way (not to the extent of London) the cost of living is lower. Therefore she could quite easily quit work and live off the money from the rent.