Different hours in term time and holidays? Brain not functioning.

[drspouse]

I currently work 0.8, 4 days a week, nice and simple.

I'm wondering about working till 3 one or two days a week when DC2 goes to school (or maybe when DC2 is 3 and could go to the school nursery).

But then there's holidays.

Can anyone clever work out for me what FTE I'd be doing if (assuming a regular 9-5.30 with an hour for lunch contract) I did:
3 days full time
1 day till 3
1 day off
Extra day off (the 9-3 day) in the school holidays? We're in England and have fairly standard holidays, and I'd take annual leave for any Inset days so it's just the main weeks holiday.

My brain can normally cope with Excel type questions but we have a lot of loud building work today!

You would need to say what normal full time hours for a week are and whether any of your Woking day would be unpaid e.g lunch and whether this would be different on a9-3 day

As above 9-5.30, forgot to say it's a 37.5 hour week (give or take) so an hour for lunch, unpaid, fairly standard.
I imagine I could work through with a sandwich at my desk (which frankly I often do), or have an hour, or have say 45 mins. I'm more trying to work out a ballpark figure.