Very unusual taking cannabis only would result in a 'murderous rampage'. Peace and quiet more likely. However, as you suggest, it's easy to allege a violent offender was on cannabis even if they weren't.
Weed has always been available here, illegally, to people of all ages and backgrounds. Might as well make it legal for adults, although the RTP won't be too happy, for obvious reasons.
Yes, not the best destination for the OP given the tone of his comments. Problem for him is most immigration authorities around the world can be awkward to say the least.
There are socialist elements in the NHS, the Police, the civil service and in iocal government who hate the UK and want to bring it down. The way the ambulance service is being run is just a tip if the iceberg.
Never had any problems of this nature with VFS who are efficient and helpful, and have never retained my passport. I suspect you will get a response after the current holidays.
Covid numbers world-wide are totally unreliable, being either under-reported or over-reported in many countries. Impossible to know what's really going on.