Upvote:1
There seems to be some partial information. The Department for Transport responded to the tweet in the question:
https://twitter.com/transportgovuk/status/1438898310375411728?s=20
In that tweet, they posted this link: https://www.gov.uk/government/news/new-system-for-international-travel
On that page is the following paragraph:
From the end of October, eligible fully vaccinated passengers and those with an approved vaccine from a select group of non-red countries will be able to replace their day 2 test with a cheaper lateral flow test, reducing the cost of tests on arrival into England. The government wants to introduce this by the end of October, aiming to have it in place for when people return from half-term breaks.
That's still rather ambiguous but a bit of further research suggests that this is probably at some point during the week commencing 25th October.