Following are some useful links to help you plan your trip.

 

Comparison Sites - These sites are really useful as they allow you to check several sites at once for flights, hotels, etc

 

travelsupermarket.com - Compare flights, hotels, car hire and package holidays here
sidestep.com - Search for flights, hotels, car hire, package holidays and activities

Flightchecker - Money Saving Expert's budget European flight comparison site

kayak.co.uk - Flight comparison site
Dohop.com - Flight comparison site

skyscanner.net - Flight comparison site
hotelscomparison.com - Hotel comparison site

carrentals.co.uk - Car rental comparison site

 

Flight booking sites

 

Expedia
Opodo
Ebookers
Cheapflights

Last Minute

 

Hotel booking sites

 

Alpharooms
HotelPronto

Octopus Travel

EasyHotels - Easyjet's hotel site
Hotel Kingdom - US hotel bookings

General

 

Money Saving Extra's Guide to Cheap Flights and Hotel Cost Cutting
A very useful site with advice on how to save money and links to lots of other travel sites

Lonely Planet - Lots of info, tips and useful forum for the independent traveller
Fodors - Useful travel tips, articles and forums
Trip Advisor - Hotel reviews and useful travel forums

Seat Guru - Information on airlines seating, inflight information, etc