An approximate answer
I had a busy summer, I'm a year 2 Captain.
This months pay was just over 8000€. I paid 800€ Swiss tax. Therefore, I receive 7250€. As Wizzaird said, UK tax remains to be paid. Which I put £1500 aside for every month - on top of the Swiss tax.
So, about £5000 after all stoppages. But it depends on lots of factors:
Base, contract, prior experience, training pay, management contracts, CRMI pay etc etc....
The company tries to offer a commuting contract of 6/4 or 6/1/6/7.