@saraclara I know that's just one hospital, but the national stats which I'm not about to search for are clear that double vaxxed people are very largely protected from fatal outcomes and serious illness. There are not "many" for whom breakthrough infection has resulted in a critical condition.
I think you and @FreshFreesias are using "many" in different contexts.
The PHE data already linked to above shows that for weeks 32-35 this year, 2,381 people died within 28 days of a positive test. 1,659 of them were fully vaxxed - as in, more than 2 weeks past their second dose.
1,659 out of 2,381 could reasonably be called "many", which I think is the way @FreshFreesias was referring to it.
However, as discussed above as well, the number of double vaxxed people in the UK is well into the millions now so the number of hospitalisations/deaths needs to be seen in proportion to that, and yes in those terms there is absolutely not many of the double vaxxed people being hospitalised/dying.