Windy, the basic for M/F is £11,000 and they have to live close to Heathrow to boot.
Then on top of that they get 2.40 per hour flight pay, no other allowances or O/T at all.
18K is what BA say they will achieve and this includes the flight pay of 2.40 which, some of which, they will need to spend on food and drink etc. while away especially in places like Hanenda(Tokyo).
It's early days as yet but so far I have not met one M/F crew member that has taken home more that £1000.
Hope that helps clarify things for you.
The CAA scheme which all airlines in the UK use (unless they have agreed something more restrictive as their scheme with the CAA) can be seen in your manual. You will find I am sure a page giving you the maximum duty hours depending on the start time and no of sectors that you can operate without captains discretion or the use of a bunk. I am sure if you look, 15 hours is the largest number you will see. Positioning after is a separate matter and the same chapter in your manual will also tell you about that.
Hope that helps.