Beach weekend in the UK with young kids?

[parapaul]

Kids will be 3 and 5 this summer, so quite capable of sitting in a car long enough to get most places in this country. IMO they're too young to take abroad, with all the hassle of airports, checkins, luggage etc, and to be fair, they won't care as long as they can build a sandcastle!

So, where can anyone recommend? Ideally cheap and cheerful, self catering for simplicity, and dog friendly would be a bonus...

Over to you, the travelled wise ones