600-800 pounds allowances in the summer would be unusual for fleets other than the 767 and A330, or A320 pilots covering for other bases (mainly Ltn crews).Above salary the only other allowances paid are flight allowances. Depending on the length of flight this will be around 20-30 per day. 200 to 300 per month seems to be normal for crews operating out of home base.
Sorry don't know about bonding.