There are plenty of guns in the UK, my town is known for having a huge legit gun trade, nothing illegal about owning guns when you have the correct licenses. The only guns you can't get are full autos and small hand guns. If a kid wanted to get a gun they'd have no problem in doing so.
When was the last school shooting in the uk? 13 March 1996.. When was the last school shooting in the US? April 20th 2018 and there have been 17 in 2018 so far..
I'm sorry but you don't see someone with a knife running around stabbing everyone in a school or in a concert like someone in call of duty with commando pro. Yes there are knife crime and stabbings but they are normally single target attacks or gang vs gang. But idk, kids here don't go into schools wanting to kill everyone. That's obviously a mental thing, the weapon is just an enabler