Just the HD version but seems like a decent price. Is there a difference between the UK version and the local one? I can't see anything obvious when searching…
Chromecast with Google TV (HD) brings you the entertainment that you love, in up to 1080p HDR. No more jumping between apps to decide what to watch. And use the remote to search with your voice. Subscription services may be required. Content and services not available in all countries or regions, and are subject to change. To view content in HD, an HD-capable TV and reliable broadband Internet connection are also required. Google Assistant may be required for full functionality. Google Assistant required for full functionality.
The HD has 1.5GB of ram vs the 2GB in the 4K, the CPU is also a little weaker.
Having said that I haven't seen anyone saying that it's any less useable or responsive compared to the 4K, perhaps the lower resolution helps. I would recommend you buy the one you need now as neither are particularly future proof.