regarding the national insurance and tax do you think i have to pay it also in my country Malta?
It depends if you are going to stay here for a long time regarding national insurance i.e. zus, because without it you are not eligible for health service care. Tax you will have to pay whatever fiddle the the company or yourself puts on it, someone has to pay in the end, so as I said it is better if you go self-employed as you will be able to claim a percentage back yourself.
I am not too sure what the agreement is between Malta and Poland is regarding tax rebates, but you might be able to claim the tax back for your work in Poland if it is temporary work.
do you guys pay also in UK?
No you only pay tax in the country that you are working.
So To work here in Poland i need to have all these things?
This depends, if you are going to live in Poland all your life then you will have to pay (zus) national insurance contributions for health care and pension and such like, but there are many different contracts that you can be employed with, one is a short term contract that you are providing a temporary service for a company where you do not have to pay zus, but this is often used as a fiddle to employ people so that the employer avoids paying zus contributions, which can add up to 700zl per month. Therefore, many employers prefer this method as it is cheaper for them, but it gives you nothing as regards health care and such like.
I hope that is understandable as I have a streaming cold and finding it quite difficult to concentrate. :O(