I don't know about UK prices, but a standard 2-car garage in the USA with a professionally applied epoxy or epoxy like coating costs ~$2,000.00. Depending on location, competition and exact materials and prep, I've seen it as high as $4,000 and as low as $1,200. I should note that a number of my neighbors, all thinking they could do it themselves with a kit from a home center, tried it and all failed. Nobody has that kind of surface grinder, and nobody did the level of prep that a pro can do. It's not the chemistry, it is all about the base prep.
My garage floor, poured in 1992, wasn't in the best of shape. In a perfect world, and one in which I had planned on staying in the home, I probably would have replaced it. But we moved last year, and we knew we were planning on a move in 2016 when we had it done.
We chose a polyaspartic coating which is a bit higher grade and cost than just epoxy, though it is quite similar. They used a huge surface grinder to prepare the concrete surface, and a smaller grinder to do the edge work. They vacuumed thoroughly with a HEPA filter vacuum to remove all the dust, though a lot was sucked up in the grinding process. They had their own 3-phase generator to power the grinder.
After this thorough grinding and cleaning, they mixed up a batch of fast-setting (20 minutes) polyaspartic filler, and filled in the spider cracks. Larger cracks, they filled with a fine sand just to prevent all the poly aspartic from running down the crack. They trowled all of this. Then they mixed up a slow cure polyaspartic (grey color), and when that was down and still uncured, they sprinkled the latex paint flakes all over; these were a mix of black, white and two shades of gray. When it all cured, they used a blade to scrape off all that didn't stick, and vacuumed up the mess. There may have been a spot or two that needed a touch more, and they mixed up a bit of clear fast cure and touched up. When all was cured, they gave it two coats of clear polyaspartic. The dust is dreadful, the vapors from the polyaspartic also harmful so this was all done with respirators.
Now that I live in NC, my smooth concrete floor will likely stay that way; no salt, snow, ice and stuff that comes in from the unbearable Michigan winters.
Several neighbors had it done here, most for appearance sake. If I ever decided that I need to pretty up the garage, I think I would choose James Lester's route with tiles of some kind. A fraction of the cost.
