That sort of situation is tricky, your best bet would be to work out the amount of hours that the minder would be willing to accept as a yearly amount and spread this amount out over the 12 month period.
So if it was 275 hours per month then 8 of these - 2200 hours for the 8 month period.
You are a london person so guessing childminders roughly £5ph = £11000 for the 8 months.
If you spread this out over the 12 month period it would work out to £916 per month.
However, they may ask for a retainer for the months that you are on holiday so maybe 50% for the time that you are not working.
This would be 550 hours at full pay ( half of 1100) so that would be an additional £2750
So if you spread it out for equal payments it would come to roughly £1145 per month.
Hope that this makes some sense to you!
I am a childminder in Ashtead, around 45 min drive from you and this would be the sort of thing that I would be willing to accept as long as it was all worked out properly.
If you would either like to come and see me for childcare or would like some explanation on the fees work out then email me at [email protected]
Good luck