I just got back from a 2-week trip to the UK.
I saw lots of buses. More in 2 weeks than I've seen in 2 years here in
New York.
Saw lots of panel vans, in fact about 50% of the buses I saw were panel
vans used by local contractors. Both Vanagon and Eurovan types (all
called 'Transporters').
Saw several Vanagons with high-tops, several different types but all had
side windows. Unfortunately I never had my camera with me when I saw
them.
Only saw one passenger Vanagon with square headlights - called
'Multivan'.
Saw one old Vanagon with a pop-top with the 'Kamping' insignia on the
back - no doubt a non-Westfalia camper conversion.
Lots of type 2 buses.

Another interesting fact -  I watched a TV documentary about a famous
soccer player called George Best. At some point he got into trouble with
the police and was taken to prison. They showed the scene on TV and he
was taken away in a black round headlight Vanagon marked 'HMPS' (Her
Majesty's Prison Service). So Vanagons were used by the Prison Service
in England.

In the UK, there are several types of non-VW vans not seen here in the
USA. The Toyota Hi-Ace, Vauxhall/Bedford Midi, Renault Trafic, and a
Mazda model. I also saw a lot of Mercedes vans. One of those I saw had
three rear-facing sets behind the driver and passenger seat.
There are lots of factory high-top vans of all types - the rear doors go
all the way up to the top of the high-top.