mummyred,
the minimum rest requirement in the UK is 12 hours for flight deck, 11 hours for cabin crew.
if any crew operate any duty over 12 hours, the flight deck must have that amount of rest again. i.e 14 hour day requires 14 hours rest.
Again, cabin crew can have the amount of duty minus one hour. So 14 hour duty day, earns 13 hours rest.
Rest can de reduced away from base to 10 hours in a hotel, this starts getting a bit involved and is prob more info than you really need. If you want the full, offcial run-down then check out the CAA website.
Hope this helps,
SPF.