And I'm fairly sure, going by the appendix 2 I filled in, that it is the recent 6 month payslips that are the key. If the P60 is lower for the previous year, it doesn't matter as long as the lowest payslip from the 6 months submitted extrapolates to higher than the income threshold.
Well, that is my reading of it anyway and I hope so as my P60 for 2011/12 was below the minimum amount, although this was only due to being on career break for part of that period anyway.