The Vapor-X OC does have 2 8 pin connectors, looks like an error on the OcUK listing. It's plain to see in the review you linked as well as their stock images, they must've made a mistake in the info.
What PSU do you have? If you don't have two 8 pin connectors, you could use an adapter, but I generally advise against it on principle. The Vapor-X is unlikely to be *that* much better than their Dual-X model, which does only require an 8 and 6 pin.
I find it irritating that there doesn't seem to be a reference R9 280, or if there is then they're not particularly common, as I always buy reference design cards where possible rather than cards with custom layout boards.