Hi there,
As a self-employed person with PAYE income too, I sympathise.
My understanding is that you need to be registered as self employed with Revenue, and complete a Form11 each year. (its easier to do on-line than on paper, once you have assembled the information).
Your posting is unclear - did you pay tax when you worked on those short assignments where you were 'contracts with PAYE'? If so, you will have P45's or P60s showing the tax paid.
Do you want to stop being self-employed, or stop being PAYE?
You would be paying Class S 'stamps' as self-employed (with a minimum contribution if your self-employed income is low), but they wouldn't entitle you to sign on, as far as I know.
Best thing would be to make an appointment with someone in Revenue, and work it all out.
When I set up on my own, 10 years ago, I paid an accountant to show me how to set up my books etc. (it cost half-a-day, but was well worth it).
The VAT limit (above which you need to be registered) is quite low too, so you need to consider that too.
Good luck