Is being paid cash in hand the same as self employed?

-I started a new job this year and was told that my wages of 拢6.00 p/hour, 拢102.00 a week, and i was responsible for paying my own national insurance and tax. I phoned the self assessment helpline (in my previous job of same earnings, i did not earn enough to pay any tax or insurance) and was told that i was not classed as self employed as the only basis my employer has, is the fact that i must pay my own deductions and was told that it is up to the employer to either pay them on my behalf, OR send in a return every month to the PAYEE dept saying how much i earnt and so i wouldnt be eligable to pay anything. I was told that you can not just hire anyone and say that they have to pay their own contributions as there is certain criteria to meet before i can say i am self employed, which i do not meet, and therefore i am classed as a worker or employee, and either way i am not responsible for the contributions, but my employer. I have informed EVERYONE (tax credits, inland revenue, local council etc) when i first started the job that i worked at XXXXXXX and what my wage was, so if i was trying to work illegally then i wouldnt have told anyone. I didnt register for self assessment as i was told it wasnt nessassary as i was not classed as self employed. I have asked my employer to put me on the books and do it properly and she is still adamant that i am self employed, but the tax say i am not? I do not know what to do, as if i dont register as self employed i am worried that they will think i am frauding (even though i told tax credits and other benefits i work and how much etc) and if i do then its like admitting im wrong for not paying my own tax, even though that wouldnt be worked out til next yr but wouldnt earn enough to pay anything anyway???!!! Anyone give me any advice as i really am stuck on what to do, i have been on touch with different dept all day and everyone says she can not just pay me cash in hand, from her purse, no wage slips or anything and then tell me to sort my own out, as i can not prove how much income i get for my housing and tax credits, and i cant afford to live without them. I have done nothing wrong except find a job, for 18 hrs a wk so i can support myself and 3 kids, told tax credits and everyone who i thought needed to know, and now, find out its all illegal and may end up having to pay back money from april as she is claiming im self emplyed not an employee............