The problem with the so-called "green list" is the testing requirement. You risk being stranded at your destination if you record a positive test before your return (and let's not forget that LFTs are notoriously fickle and prone to false positives).
Then if the experience of last year was anything to go by, the biggest hurdle on returning is the AVAILABILITY of a private PCR test. I had friends who went to Cyprus (where they required a test before flying and one on arrival) and they had to cancel because there wasn't anywhere near enough capacity in the whole of the UK at private labs. Prices were astronomical because of this. In the end, after a fraught week of phoning around they could only find a test in Edinburgh (they live in Exeter) and that was £350 each!
The same rigmarole happened at Christmas with the Canary Islands. Before the travel window slammed shut due to the Kent variant Spain announced all arrivals would need a PCR test. Within a day, EVERY private PCR test in the country had sold out and people were forced to cancel again.
In both these scenarios, there were so few people travelling and even with tiny numbers the system was inadequate. A fool could predict that it will go tits up as the hoards return from the May half term.