It's not Florida, but I'm sure it'll be lovely :-)
Any tips for Northumbria?
Well, there are some of the best beaches in the country in our neck of the woods, and though of course you're not staying on the coast it is not too far to drive for the best ones. I would say that your "must do" things are Bamburgh Castle, especially as Bamburgh beach is so magnificent, and extra fun for kids with it's dunes http://www.bamburghcastle.com Bamburgh village itself is nice. And Holy Island (Lindisfarne) is so beautiful with loads of history, and again, good for the kids when you are driving over the causeway to get there. The road is only open at certain times of day when the tide is low, and it's fun for them to look back and see that the road is no longer there, but is now the sea! http://www.yournorthumberland.co.uk/...es/holy-island
A visit to Seahouses to go on a boat trip (use Billy Shiels, he's a legend in these parts!) out to the Farne Islands is lovely. You will see seals and puffins, as well a lot of other seabirds, http://www.farne-islands.com Seahouses itself is a bit touristy but there are rock pools to play in as well as excellent fish and chips!
A 10 minute drive from Alnwick takes you to Low Newton. There's nothing much there at all, except a nice beach that leads to Dunstanburgh Castle with great views, but the little pub there, The Ship Inn, sells amazing fresh crab sandwiches. I advise you are there for around 12 noon when it opens, as it is so popular that it gets full up very quickly! http://shipinnnewton.co.uk Of course, you are just a stroll away from Alnwick gardens and Alnwick Castle, which are both kid-friendly, and as you know the castle is where some of Harry Potter was filmed. They have Harry Potter themed activities for the kids http://www.alnwickcastle.com