Quidco is one of a range of cashback sites.
There are several excellent deals, from up to 12% cashback on Expedia hotel bookings to 2% back on Virgin Atlantic flights. BA has a range of discount deals as well. You can access the deals here:
Not in themselves enormous, but over the year it’s quite easy to get a good proportion of your annual travel spend back, often in addition to any sale or other discount available.
Highly recommended, and once you get into the habit of clicking through quidco before you book, it’s easy money.