Hello Bel,

If that message is from the British Embassy (sender ending in .gov) then it means just what it says, in that your visa will be despatched shortly.

It's very rare that folks receiving that message have done so in error, but as with all automated messages it's possible that it was sent in error.
To be 100% certain you'll need to wait until you have you passport in hand and can see that visa.

I'm confident enough though, to give my advance congratulations
Well done