Ofcourse they favour those with turbine time and an IR.. even more if they have offshore experience and 2000+hrs. But I know of quite a few guys that did the IR with somewere between 200 and 700 hours and got hired by an offshore operator. I know of an other guy that instructed till just over a thousand hours and got a sic corporate job because he had created a good network while working as a FI. Truth is that all had to pay for the IR themselves.
It might be hard to pay the bills as a flight instructor, even harder when you have to support a family or have to pay off loans, but your experience is growing and at some point you will be attractive enough for an employer. That will somewhat reduce the risk off paying for the IR yourself.
If all doesn't work out in the UK there are always options somewhere else on this planet when you have a 1000 hours or more.