Did you agree cancellation rights?
OK. I presume they still have the boat to sell?
Were you buying outright or using finance?
In that case, you are entitled to at least most of it back
The starting point is that you are locked into a contract and breaking it would be unlawful.
However, they only have a claim for the sum of their loss and they still have the boat to sell to another.
They may get some readvertising costs. They may get some admin costs. That would be very low.
the majority of your deposit should be returned.
Can I clarify anything for you?
Well, what I said above?
There isn't an act of parliament on the point
Not unless you did the deal remotely and then you would have cancellation rights automatically.