You can claim Maternity Allowance, as I did last year, although it was hard work to get. My baby was due in December 2012 so was entitled to it from October. I didn't get a National Insurance bill though until November 2012 which had a due date of January 2013. I couldn't claim a penny until that NI was paid. (Ridiculous I know). We got there in the end though and it was all backdated.
I think the allowance dates were something like from 11 weeks before the EDD to 24 weeks after the birth.
Then I don't think you can claim anything, of course you can take as much or as little time off as you need as you're the boss and you could keep paying yourself if the funds are there but as for any official maternity pay I don't think it exists.
Your contract with your part time employer should state what maternity pay you are entitled to so I'd check with the HR department. As for your self employed role it really depends if you are set up as an individual or a company. Best place to check would be the direct.gov site I think.
I work part time as an employee and had SMP through the company last year. I have now begun to develop my own company and wanted to find out a few things as I am looking to get pregnant within the next year.
Can I get mat pay through employment and self employment? Can I go back to my self employment before employment? How many weeks must I be off work after the birth?
I'm undecided whether I will go back to employment but just keeping options open