Do you get an overnight allowance in excess of the flight pay and duty pay to cover your meals etc at your hotel? Or are you picking up the tab for your dinner?
No not really. Just an UK or non-UK incidental allowance for each night-stop on top of your 'flight and duty pay'.
The answer to your overtime question is complicated.
You can only bank excessive hours from the the original rostered line or gained through trip swaps. Any other work you volunteer to work in excess of your roster is paid at varying rates depending on 'circumstances'.