Yes, late deals to exist, but they only coe about 1-2 weeks before the holiday starts.
There are plenty of holiday search sites, like teletext and icelolly. But bear in mind these don't offer the same security as a travel agent such as Thomas Cook etc..
The reason I say this is because, even though they appear to be package holidays, they're not, the travel agents that put these holidays together basically go around a pick out the cheapest flights, accom and what ever else from several companies.
What's wrong with this? Well, if anything goes wrong while you're on holiday, **** accom, flight buggered up, you won't be able to rely on the agent to sort things out for you.
Obviously, if you're not going that far and you're going to save a substantial ammount, then it's not that big of a risk. It's food for thought, I'm by no means saying don't use these cheap travel sites, because they have some cracking deals, just saying that you should take this into consideration.