I flew BA to Lisbon on the first weekend of the UK school holidays in April. (Not my choice, it was for work). The airport was very busy but seemed to be moving ok. (I am fortunate to be able to use the First Class check in and screening at T5 - so I have no idea how security was coping).
I loved the upgrade but I wished my bag could have joined me. It took BA 2 days to get it to me.
I suspect the ramp services are really feeling the pinch as who wants to work in all weathers for not brilliant money? BA and other UK airlines are really struggling to (re)hire ground staff after the pandemic.