Why do people have to go away on holiday anyway? All that is necessary for a family holiday is for all the family to book leave at the same time and a week together can be enjoyed at home just as much as going away.
For children just having their parents undivided attention for a week can be exciting There are ample things a family can do when they are all together, whether they live in a town or in the country. Many museums have free entry, there are parks and gardens. Just walking somewhere can be fascinating if you open your eyes and look around. How many children will have gone walking on footpaths round their village if they live in the country. August is prime blackberry picking season, (and wild apples and plums). My 2 GC are already talking about more Twilight Walks, when they come for half term. Going out just as it begins to get dark and coming back as the night closes in. Armed with torches we listen for owls and foxes and imagine ghosts and hobgoblins.
If the weather is awful, charity shops always have board games (probably a novelty) and jigsaws(ditto) that cost very little that can become a family activity.
It isn't necessary to go away to have a holiday. We've done it in the past.