It's almost impossible to give sensible advice based on so little (almost no) information, which is why the answers you get here will tend to be somewhat negative or sarcastic (my speciality, so apologies in advance)
Big question - how old are the kids? (funds in place for how many years?) How easily will they adapt to a foreign country / language / make friends etc.? And when they finish school, what prospects will they have (basically pretty poor, and they'll probably want to return to the UK asap, unless they're content to work in your cafe forever)
Don't underestimate how hard it will be to replicate the success of your UK business, in Spain. There is so much that could go wrong. You've obviously got some capital behind you, which is great, but to paraphrase someone wiser than me, "the best way to make a fortune in Spain, is to start with a bigger fortune". There's nothing wrong with following your dream and giving it a go - but you must think of the kids first: don't jeopordise their future for yours.
Just my humble thoughts on the matter, hope it doesn't come across as rude or judgemental.
Good luck