Gee

When I was temping (not that long ago) I hade to fill in and sign various papers which, essentially, put me on the books of the agency.  This required that I do my bit (availability, timesheets, representing the agency when on assignment) and they were held responsible for PAYE, NI and other employment law for employers type of stuff, etc.  

Did you not sign similar stuff for this particular agency (or any of the agencies)?  I would be surprised if you did not sign something for them which would give you some protection under the law (for employment and tax purposes!).  It would also entitle you to payment for holiday time accrued (including bank holidays and time taken as holidays!)- I am, of course, assuming that the current employment regulations here in the UK are also enacted in NI.

I would not have assumed that you would be entitled to a contract from the company direct until such time as you were officially a permanent employee (even temp to perm have this) and you would also be on the agency books (pay etc) until your permanent position kicks in!

I think I have this right.

Jess