It's ridiculous that no one in government seems to ask the "what will happen if..." question.
"What will happen if we announce that everyone over 18 can get a booster?" = lots of people will try to book said booster on the NHS website.
"What will happen if we announce no isolation for covid-contacts, but take daily LFTs instead?" = lots of people will try to order said LFTs on the NHS website.
"What will happen if we make both of the above effective around the same time?" = lots and lots of people hitting the NHS website at the same time.
Either do the work before the announcement(s) to ensure the increased capacity can be handled, or just say "in preparation for these changes which will come into effect on xxxday, the NHS website will be unavailable between the hours of xxxx and xxxx whilst upgrade work takes place."
Or in the case of LFTs, let's check that our delivery partner(s) can handle the extra demand, before we create chaos.