I am a recent graduate (4 years biology major + 1.5yr secondary education certificate) living in the US.
Not much here that will help you find a good job with the opportunity of advancing yourself in Poland, I'm afraid. You're chances are so much higher in the States, that moving to Poland would be a very unwise choice, especially at this point in your career. Wages for teachers in Poland are downright abysmal. In the rosiest scenario, your looking at no more than $12,000 a year, and probably a lot less. Plus it's a dead end job with a very low earnings ceiling.
A BS in biology isn't worth much on the job market even in the States, and a lot less in Poland. You'll have to beef it up. For example, taking a year-long course in medical technology will open up a lot of doors. Job prospects are excellent and future earning potential are OK, both better than for a secondary school science teacher with only a BS.
Even better, go into biomedical engineering. Both job prospects and future earnings potential are stellar; quadruple or more than for a secondary school science teacher, with no ceiling. Before you do so, take a year or two to intensively brush up on your math: trig, geometry, calculus, linear algebra, differential equations, probability and statistics and formal logic, at your local public college. In the long run, this will save you a lot of money and grief. Also, bring your biochemistry, organic chemistry, physics, physical chemistry, molecular biology and microbiology up to snuff. Those courses should have been part of your undergraduate studies. If not, take them for credit at your local public college. Doing so may cost you a year or two, or even more, if you have to work, depending how much of this you have already done during your undergraduate studies, but having a very firm basis and good grades in math and chem/molecular biology will enable you to get into a very good engineering program at a very good school, and hugely lighten the load once you get there. Graduate in biomedical engineering from a good school, and you future is very bright indeed.
The best plan would be: get your medical technology certificate, work part time in a hospital lab while you brush up on the math and other courses I listed at your local public college, making sure you get excellent grades, then get into a good biomedical engineering program at a serious, but not expensive, school of engineering. With the math and science prep behind you, you will be able to continue working part-time as a med. tech as you study. It might take you seven or eight years, but when you finish, you'll be earning a hell of a lot more that you would be at thirty with your present qualifications (as a secondary school teacher, your going to hit the earnings ceiling pretty quick). You'll have a degree that is worth gold on the job market, job offers out the gazoot, a continuous employment history, little in loans to pay back, and countless opportunities for further advancement (like working a few years, and then getting a serious kick-ass MBA from a prestigious school).
