Comparison with Thailand is somewhat flawed.
In the UK we have elections every 5 years when the electorate can express their views and change leadership. Mostly true despite the attempts to subvert the democratic process during Brexit.
Thailand has a military coup or crisis with about the same frequency. A constitutional monarchy (in theory), it is effectively a military state. They have the capacity (and willingness) for suppression of opposition in a way which would be untenable in the UK (and most of Western Europe).
I am not defending UK covid performance but there are far more appropriate comparators. Thailand clearly acted early and forcefully in a way which the UK simply would or could not.
In some respects through their actions Thailand may be storing up future problems. I understand that vaccine rollout has covered only 1 or 2% of the population. When, in a few months time, Europe and the US are largely open for business as usual, Thailand will still be locked down.