Also, make sure you meet the rest of the criteria on the full list. I think this includes evidence of all tax paid for that year, SA300 statements etc.

As proof of ongoing self employment I phoned the tax people and asked them to send a statement showing the NI contributions I have made. As it is taken 3 months in arrears I explained this in a letter. I also provided all bank statements for the last tax year and the current year. I gave them no reason to refuse the application.