I don't really understand your question, Eve. (Sorry!). The statutory annual entitlement to paid leave is calculated as 5.6 x the number of days worked per week (but with a total limit of 28 days).
So, assuming that your husband works 5 (or 6) days per week, he's receiving the legal minimum. You, on the other hand, are getting the legal minimum plus an additional 7 days that are written into your contract. So, up until that point, there's simply no calculation to be done.
If one, or both, of you is starting or finishing a job though, the number of days holiday that you were, or will be, entitled to in the relevant part-year will be calculated pro rata to the entitlement for a full year. In order to do any relevant calculations, we'd need to know the start/finish dates for your employment.
As an example, let's say that you were both to leave your current jobs on Friday 27 August. That's the 239th day of the year. To find your holiday entitlement for the part-year that you'd worked, you need to divide 35 by 365 and then multiply by 239. (Ans = 22.92 days, which any reasonable employer would call 23 days). The calculation for your husband though would be to divide 28 by 365 and then multiply by 239. (Ans = 18.33 days, which most employers might well round up to 19 days).
(The foregoing calculations assume that your employers start their 'holiday year' calculations on 1 January each year, as most, but not all, do).