You do not have to be unemployed to get social welfare assistance. I had the exact same situation where I was not fired, but just wasn't getting any more work. I was able to sign on.
Eventually I did get a P45 when it was clear the situation wasn't goign to improve.
Pop down to the local Citizens Information office. It's generally useless trying to talk to teh Social Welfare unless you already know what your entitlements are, unless you get a decent person behind the counter.
You should be able to claim jobseekers allowance or benefit as least, as well as Rent Allowance. The sooner you act, the sooner you'll start getting income.
meanwhile call back your employer and ask them, as has been suggested. it migth be a misunderstanding.