I live in Glasgow and have used powerful binocular before.
I have seen many aircraft including many British Ones, BA 747/777 presumably from London, plus also Lufthansa and SAS 767. They will all be heading for North America. It depends on the Atlantic ATC track as to whether you see them or not. Pan Am flight 106 would have headed up across Glasgow Area had it not exploded further south at Lockerbie.
Hope this helps