The approach is much more of a crossover/all round boat. You will be able to paddle some moving water with this but it is not a WW specific design. Kinda like a sled on a ski hill.
I understand not wanting to invest heavily into a "maybe" sport, so it seems you have two options: buy an older WW kayak ($100-$200?) and hope that she likes it or buy something like the Approach that will work for other activities in case she doesn't like it. Only drawback with the latter is that if she DOES like it (and who wouldn't, it's the coolest sport out there
)you'll soon need to buy a new, WW specific, kayak.