Anyone else wish you could start a tax return during its own tax year? So you could enter things as you go along, especially those things that don't get summarised for tax purposes at year-end (like PAYE).
Last few years I've had a one-off taxable payment around the end of January (about £200-ish). By April, when I can start filling the tax return, the only record I have of it is the payment into my bank account. This year I don't even have that, as I've closed the bank account in question.