So you are looking to go abroad - 2 adult and 2 children for £700ish?
I hope I am wrong but I don't think you will find a holiday at that price. You might if you went later in the year though.
I think a lot of people are thinking the same as you due to this weather but August is always an expensive month.
I only said to my Husband today, can you imagine camping in this weather and having to get to the Club House at night?
After getting all dressed up, you would have to drive to it.
Keep your fingers crossed that the weather will improve and you will have a lovely time.
You could look at hotels in the UK as some have indoor pools etc and several have offers on at the moment.
You might have to make it a shorter break though.
I wish you all the best!