That is indeed the stumbling block. All this LED light is relative new, and most of us have not the available cash to go out and buy these expensive units just to try them out. I will say that there is some good LED lighting available for planted tanks. But I do not know which they are, and have not yet tried any.
I don't understand the UV thing. UV sterilizers kill bacteria, but in that situation the water is passed through the unit, so the fish are not being exposed to it. I'd want to research this a lot before trying UV over the tank.
There is one LED unit that I am hoping to buy, the Marineland Double Bright. Here's a link to data from one of my local stores: Marineland Double Bright LED Light Fixture (18-24 Inch)
I've not tried this yet, so am not saying yea or nay, but I'm having difficulty getting sufficient light over my 29g and 33g and have almost decided to go with one of these. They come in various lengths, and each is adjustable a bit, so I linked the smallest for you. I'm sure these are available in the UK, I think I've seen them in PFK.