Hi Pete,
Your SEIR isn't a qualification you can practically use in JAA land, as in the UK an IR has to be ME to be actuallly uesable.
I'm assuming you've tried all the offshore companies? Their reluctance may be the additional costs in changing your IR to a MEIR. Particularly if there is a ready supply of MEIR candidates applying.
So far as I can see your options are:
Find a friendly owner (as has been offered).
Offer your services as a non type rated second pilot.
Use the money you'd be spending to get an FI ticket etc etc to transfer your SEIR to a MEIR and then apply to everywhere again.
It's a case of knocking on every door I'm afraid and seeing if any company can make use of what you have.
Very best of luck.
FW