long reply part 3 and last
"Compensatory rest" is normally a period of rest the same length as the period of rest, or part of a period of rest, that a worker has missed.
The regulations give all workers a right to 90 hours of rest in a week. This is the total of your entitlement to daily and weekly rest periods. The exceptions allow you to take rest in a different pattern to that set out in the regulations.
The principle is that everyone gets his or her entitlement of 90 hours rest a week on average, although some rest may come slightly later than normal
The European Court of Justice has ruled that compensatory rest should be provided immediately after the end of the working period
I think that means if you get less than 11 hours one night you have to have 11 hours plus what you missed the next night
For more info try
http://www.dti.gov.uk/employment/employment-le gislation/employment-guidance/page28978.html
or www.acas.org.uk
sorry this was long and horribly boring - hope it helps