From a measly one-month course? Which is hardly intellectually demanding? Get real.
Looks like you misunderstood, perhaps deliberately. The bit that said:
it takes more than just a 4 week course
You're talking about guys who have been here for ten or twenty years, the battle-hardened survivors of thousands who have tried
Half of the long termers are washed out people spooling out Headway for private language schools, or deadbeat Americans doing so-called 'conversation classes' which they imagine means just chatting.. Another quarter do or want to do other things like proofreading. The rest have other strings to their bow or a very high skill level, and can earn very well indeed.
People who specialise in Medical, Legal, Technical, Petrochemical, Financial, Diplomatic, Military etc, and have a sound theoretical and methodological base are a different kettle of fish - they earn well, however must be based in the capital, be prepared to travel, and actually know what they're doing.
For a paramedic, there are plenty of opportunities to use their professional background; they must however be able to sell their services to Doctors, Nurses, Dentists etc., mostly ones who are considering working abroad. Solid UK/RoI experience would give the OP the credibility to do this and an understanding of how to achieve it.
He would do well to talk to any Polish colleagues he has back home, and gauge their reaction (as well as make contacts). Contact with the various professional bodies in Poland once he's arrived wouldn't go amiss either.