If you use quidco to book through expedia or hotels. com you will get 10% cashback. These offers finish at end of day but I have to say that they are frequently on offer and I have 10% back on both in the past.
Also Thomas Cook has a 4.5% offer today.
For my holiday in Mexico last summer I had researched the normal way and found the best deal I could get was with hotels4u. I then went on to quidco and found there was a cashback offer with them. So I used quidco to enter the hotels4u website and got £103 cashback within 2 months. At that point I hadn't even paid that amount as a deposit
Please follow the quidco advice for getting cashback. The main one is that you get rid of all cookies for the site you want cashback from as it has to show on your computer that you first entered the site via quidco. I have a browser I only use for quidco.