Philip, I have no direct knowledge about the tool scene in the UK. But, if the commercially-made tables you are looking at are "affordable", they are almost certainly made in China by one of several manufacturers there. If they look similar, they are likely simply re-branded versions of the same product. We see the same sort of similarity between brands here in the U.S., since almost nothing is made here, either.
The sliding table design looks interesting at first glance, like the sliding-table cabinet saw. If part of the table slides, however, there has to be some tolerance to allow for movement. That movement has to translate into stock movement (relative to the bit), as well.
The components that make a router table most useful or convenient are the plate design, the lift (if any), and the fence. The rest is just a flat surface into or onto which the other components are mounted.