Bright Room in Family in SW7 with reduced rent

I, the landlord, am a single mum of two easy-going children of 10 (boy) and 12 (girl) years old and a very friendly small dog.
I have a bit of an alternative rental proposal for the right person.
My children and I live in a bright three storey flat in South-Kensington – very central (Zone 1), close to Gloucester road Tube Station with direct access to Piccadilly, Circle and District Lines. We are just 7 minutes on foot from the Imperial College South Kensington Campus. Our house gives on a leafy and quiet private garden square to which we have access for sunbathing – or studying – when the sun is out. Very important in those COVID times !
I have a single room to rent with a twist. The room itself is very bright with a splendid view onto greenery in the quiet garden cul-de-sac.
I am looking for a female student who would ideally stay until next summer or longer. The normal rent for the room would be £170 per week plus £30 for all bills. I am ready however to reduce this rent to a total of £ 120 per week against some simple services which this person would render to the family, according to her study schedule. These would include helping to prepare breakfast in the morning, (rarely) dropping the children to school next to the tube station, picking one child up a few times a week at 3:40 and bringing him home on foot (10 minutes), walking the dog and preparing some easy meals for the three of us around 7:00 pm in the evenings. I would also need this person to do a maximum of two – often less – babysittings a week for the evening or overnight, if I travel. On those days, all what is needed is an adult presence in the house, no childcare per se as the children can entertain themselves. All in all, those services would not represent more than 7 to 8 hours per week at a maximum and week-ends are always completely free.
I do realize that a student would have a specific study schedule and I am happy to work around it.
I realize this is a different proposition to a house share with other students/young professionals. We have had young females staying with us for several years now and they all enjoyed the family environment, the very quiet space of their room and the very central location.
Just a few additional practical details. I would expect a three months payment in advance of the full rent, while I reimburse weekly down to the £ 120 per week upon delivery of the services. I would also want a 5 weeks deposit.
What we are looking for is to welcome a new responsible member in the family, even if we are all very aware of the personal needs of that person and her desire for her own quiet space and time. We know how to make this work with the right type of person.