Re: £22bn?
Well, I think a lot of the budget has actually gone on the labs (and buying and losing LFT kits...).
I think the issue, though, is not where the money has gone but what it has achieved.
The only purpose in mass testing is if you take some meaningful action as a result and clearly that hasn't happened. If all you want to know is how many people are infected you could do that with statistical sampling of far fewer people (as the ONS survey does).