Hi there
As Gizmo says, check the website for the airport you will be flying from, and check it again not sooner than 48 hours before you leave. Or look on the Department for Transport website because they are the people who imposed the hand-luggage restrictions - complete with the idiotic proposition that 100ml of toothpaste is a cleanser but 110ml of it is potentially a weapon of mass destruction.
Also, at Hethrow now they have a sort of cage thing behind each check-in girl. If your hand luggage won't fit into the cage, it has to go in the hold, so make sure you get teh permitted dimensions for hand-luggage and that yours doesn't exceed it.
If it is an unused
PR visa and you have one-way tickets, most airlines will give you double the normal baggage allowance free of charge, but check with the airline.
The other thing is get to the airport EARLY. The new restrictions were causing the most appalling queues at Heathrow when my mother flew from there last October.
Gotta run. Time to leave for work.....
Cheers
Gill