Problem is we just don't know how bad it's gonna be yet. It's only gonna be varying degrees of bad tho. Cannot see a lockdown under any circumstances except the NHS getting overrun. To try and suppress the virus just for suppression's sake seems pointless if this variant is going to become the globally dominant variant because there's no way we're gonna keep it out unless we close all borders permanently and lock down completely under house arrest, and that's simply not possible.
Lockdowns also bring in a whole host of other problems, too many to list. Undoubtedly, the official position is that casualties are acceptable, the question is if the NHS can cope with what's coming. If it can't, I'll expect severe restrictions. If it can, nope. We won't know for sure until it hits and we see just how well the vaccines hold up and see the disease severity in various groups.
The ball started rolling again the second this variant emerged. There's no stopping it now, imho.