Thank you all for your thoughts and ideas.
The retention rate of 55% (according to a sample payslip I received from an Irish accountant company) was after an addition of about 10% of expenses, on the take home pay. It looks unrealistic to be able to claim every month an amount of in excess of 10% of your gross salary, at least IMHO. That would mean one has to spent every month 1000-1500 Euros only on company expenditure, something that looks difficult to achieve. I was also sent a list on what you can claim, and is not a lot. Flying out of base would qualify basically to claim all expenses you incur, but its your money you are spending at the end of the day so, no real increment from the 55%
Apparently 80% as it was said, was for those having an old contract with companies set up elsewhere other than Ireland, and that can be done no more.
Furthermore, I was told that if you are in a base where there is not much flying in winter time, then obviously you are looking at a salary of 30-40 hours gross, making the home pay on such months, very very low. Is that also true?