Paying a deposit for an independent place and losing it because you eventually take a state place isn't the worst thing that could happen - if that's what we do, we'll have paid a small price relative to the entire cost of independent education to secure a range of options that parents would cut their arm off for.
What I do fear is paying a deposit on our second-choice independent because the deadline hits, and then getting a place at our favoured independent. We have money set aside for school fees and inflation, but very limited income, so it doesn't really allow for too much wastage of the odd couple of thousand here and there.