Both of the displays you linked have TN panels. On 144Hz displays TN is the only choice; otherwise avoid it. You want to see IPS, VA or some derivative. Also, if viewing angle is indicated as 160-170 degrees, it's TN; non-TN displays have almost 180 degree viewing angles.
I'm not familiar with the UK market and didn't look very hard, and better prices are probably out there, but at least some IPS displays are available around £130:
HP 23xi
LG 23EA63V
Same place had a HP 22xi for £120.
The HPs at least are good (apart from lacking ergonomic adjustments a pricier display would have). 23xi is known to have quite low input lag.
You could consider buying used as well. Displays are typically long-lived, and many of them have long warranties that make them largely risk-free to buy used.