7.30 to 6.30 five days per week is a lot of hours, so whatever form of childcare you choose it will be costly.
I'm on Surrey/Berks border and a childminder for those hours for 2 children could easily cost £110 per day, £550 per week (£5 per hour, per child). A nanny in my area is likely to be £110 per day gross salary (£550 per week), plus employers NI of £56 a week, plus activities, mileage etc.
Weekly Expenses Kitty (for activities/outings): £5 per day, you may find the cost increases during school/nursery holidays. Based on a 48 week working year, nanny working 5 days per week, £5 x 48 weeks x 5 days= £1200 total.
Nannies Travelling Costs Whilst On Duty: If your nanny uses their own car, then employers would usually reimburse the cost at £0.45 per mile (this is known as the Approved Mileage Rate).
How many miles your nanny would do will vary. Consider the usual mileage they would do to take children to school/nursery and back, to get to toddler group, other outings. I would say that I do an average of 3000 miles a year (nannying 4 days per week in a semi-rural location). Start recording the mileage you do in your car during the week, you may be quite surprised how quickly the mileage adds up even if you are just going to the local shops, library, playground, woods, PYO farm etc.
For a 5 day per week nanny I suggest factoring in at least 120 miles a week… so £54 per week, £2592 per year (48 weeks).
While your nanny is on duty, you give them food and drink. Nannies don’t really get a lunch hour, can’t leave your children home alone. So food is seen as a sort of perk in compensation for working without a break. How much does that add to your weekly food budget… I am not sure. Nanny will eat with the children, so should eat the same thing (excluding baby food). If nanny wants something different, I feel nanny should be buying that themselves. So increase in food bill, extra £3 a day maybe? Heating/Light will also be used more as nanny is around during some of the day, so another few pounds. If comparing with a childminder/nursery, lights wouldn't be on at your home, heating may also be set low. If comparing with you staying at home, then there won’t really be much of a difference at all. There is also some additional wear and tear on the property. Shall we lump all these types of cost together… say £8 per working day. Suppose you could include cost of Employers Insurance in that (it is usually part of your home contents cover, check your policy). So 5 days x £8 = £40. 48 weeks x £40 = £1920 You will need to consider if this is realistic or not given costs of heating/lighting your home.
Nannies do light housework in addition to childcare. There are pros and cons to each type of childcare, so you need to arm yourself with as much information as possible, do some financial calculations and see what would best suit your family.
If you can find a nanny who will accept a lower salary, which certainly can happen especially for those starting out in nannying, then you can shave a £1 or £2 off the hourly salary which can make a big difference overall.