I think you need to look a bit harder and read a lot more closely. Interesting that you've chosen the year 2017/18; the ONS site does not state an "additional 50,100 excess winter deaths", it says "estimated", not additional. In addition to Seasonal 'Flu, "respiratory disease" includes deaths related to Pneumonia, COPD, Emphysema, Lung Cancer, Chronic Asthma, etc. In 2017/18, these respiratory diseases caused 34.7% of all excess winter deaths in England and Wales, i.e. 17,385 deaths.
In the year 2018/19, estimated excess winter deaths were 23,200. Again,
all respiratory disease (not just seasonal 'flu) was the greatest cause
of EWD, totalling 9,500 deaths in England and Wales.
With regard to your statement, "average weekly death rates
for England and Wales is around 10500 per week, during the influenza
winter months of 2017/18 this rises to around 12500 / 13000 per week",
did you not look at those figures and realise they were wrong? Or were
you hoping that I wouldn't notice that you've quoted the figures for
TOTAL deaths, rather than deaths caused only by respiratory diseases?
Taking the first 16 weeks of 2019, so that there is a direct correlation with the current year ONS figures for Covid-19 to 17 April 2020, total deaths from all respiratory diseases were 27,406. So, the average weekly death rate was 1,713. Compare the 2019 figure of 27,406 to the current Worldometer UK death figure of 21,678. As I've already said, the government has recently admitted that latter figure doesn't include deaths outside of hospitals, but if you look at the ONS figures, which include deaths in care homes, private residences and hospices, the Covid-19 related death rate to 17 April 2020 is 28,404, and this figure doesn't include Covid-19 deaths in Scotland and Northern Ireland. I think others may be able to understand where the FT, in an article to which I provided the link earlier, arrives at their Covid-19 death rate estimation nearer 41,000, and significantly more than the average death rate from seasonal 'flu.
By the way, I don't know why you've made the assumption that I have a "medical background", but I have noticed that when you're under pressure, you resort to snide, personal insults. Please try to be civil in future.