My RHS book says 10', Cheryl. It's usually quite accurate.

Cheal's Weeping rarely gets over comfortable arm's reach. A lot depends on where the graft is, but it is only a steady grower, and will tend to widen, rather than grow tall, with age. If you can't find one, let me know, because there are growers near me who do all the ornamental fruit trees. AND, join GOY, it's fun. Phil J

I had a Cheal's weeping cherry for many years, Spritz has the ht about right at about 10ft, but the spread was wide and most of the year it was not attractive to us. However, for the time it blossomed it was beautiful. It worked for me in a smallish lawn but it grew quite larger fairly quickly in 5 years it was a wide tree.
Quite a few tree nurseries on line sell them from £27-£50.
A company called 'Mail order trees' have a lot you could look at? They say Cheals will be a Height/ spread in 20 years: 2.5m/2.5m