Whether you want to visit far flung places or travel within the UK, you should be able to find reasonable deals with most carriers although you are more likely to find a really good price if you consult a price comparison website and compare prices across carriers and tour operators.
Lastminute and Expedia websites are also very good to take a look at, especially if you can be flexible with your travel dates as they offer many great deals at the very last minute. They also offer hotels and car hire if you want to sort out all the aspects of your trip in one fell swoop. Other companies such as dial-a-flight or TelMe are also worth looking at, and you may find the best deals are with less well known airlines.
There are some great offers out there at the moment so we highly recommend throwing your toothbrush and passport in a bag and picking up a last minute flight to wherever takes your fancy.