most 50 inch tvs will be the same with VA screen so get any LG or Samsung set.
if wanted ips go for LG 49 inch set but VA screens are better. so would defo stay on 50 inch size.
Buy Hisense Roku 50 Inch R50B7120UK Smart 4K HDR LED Freeview TV at Argos. Thousands of products for same day delivery £3.95, or fast store collection.
With motion top priority I'd consider searching for Sony models. Their newer TVs are probably over budget, especially if you buy now rather than later (i'd recommend Black Friday or later).
Limited budget would mean Sony 49XG70/XG80/XG81 models in 2019 - if you can still find these since they are end of life, they will likely be priced better.
This years (currently overpriced) Sony 49X70/XH80/XH81
Motion won't be brilliant at this price range, but the motion on a 60hz Sony TV using an IPS panel is going to be better than that of a 60hz Samsung/Hisense TV using a VA panel.
LG also use VA at 50" but IPS at 49" so if Sony is out of budget, you could opt for a 49" LG.