I want to file my tax return for last tax year as quickly as possible, as I'll be owed a refund.

In the employment section it asks for information from my P60, which typically won't be issued for a few weeks. However, I know the information as the pay/tax are listed on my last payslip from March, and the PAYE reference is on last year's P60. Taxable expenses are reported through payroll, so I'm not expecting a P11D.

Will I be breaking any rules or storing up any trouble for myself if I file my return before receiving my P60?

[Technically the return talks about either a P60 or a P45, but the latter would only be relevant if I'd left the job during the last tax year]