If you have never looked at a cashback site, give it a go now. There are thousands of companies on quidco. You dont buy anything on quidco- you just go to the sites you want through it. To all intents, you have booked directly with the company. For my holidays , I do loads of research and find the company which gives me the best hotel deal. It is then that I check quidco to see if the company is on it. In the last year just 2 of my cashbacks have been £82 and £109 from Expedia.
VERY IMPORTANT- clear your cookies before making the purchase. You won't get cashback if the company website recognises you have visited them already and done the research. I have a browser which I only use for quidco purchases.
You need to treat cashback as a bonus ie you are booking what you would have anyway. In all the transactions I have done I have only not got cashback once- and that was my fault as I didn't abide by the T&Cs of the offer.
A lot of airlines have cashback- usually only 1%, but better with you then them!. Some companies have a lot more- hotels.com have 12% Expedia often gives 12%
http://www.quidco.com/top-cashback/
I also use this for general purchases. The cashback I get from them goes into the holiday fund