I have no idea what the local prospects for helicopter pilots is in Poland (perhaps go talk to some local operators?), but if you want to fly offshore, you need an IR. A multi-engine IR costs around £35k - £40k (or more), depending on where you go and how jacked up you are. There are basically no jobs for 135-hour CPLs in the UK, and I don't believe most of the rest of Europe is much different, so you either need an instructors rating (which requires another 100 hours before you start) or an IR. The offshore companies are hiring 200-hour baby pilots, but only with IRs.
Ultimately, if you want to fly helicopters, then you should do the CPL(H). If you don't really care what you fly, so long as you get to fly, then go ATPL(A), as the initial job prospects _MAY_ be better. You're already doing much better than most in Western Europe, getting to CPL(H) level without spending any of your own money - most of us need to find £85k+ to get to CPL(H)/IR!