Re: How soon
The only hard figures I have are 1770 deaths for 2018 and 1752 for 2019. For 2020, I'm remembering Grant Shapps (in a Parliamentary Committee hearing IIRC) stating road deaths were down "70%", pro rata during at least the first part of the lockdown starting in march.
That is a very small number in the overall death rate, but there have been news reports claiming some decrease in non-COVID death rates, but it's likely we won't have any real hard and fast numbers until next year when the ONS does it's reports.
Having said that, the "excess deaths" number is calculated by looking at death rates higher than expected for the time of year based on the averages of previous years. So, again, we don't really know for sure what the actual excess death rates are yet because we don't know yet if this years "expected" deaths rates have changed.
Anyway, all that said, I accept your point that the figures/estimates/guess may well b e wrong, I Donald Trump your claim with "well, I said THOSE deaths dropped significantly, not necessarily that the number is significant in the grand picture :-p