As you say, you don't see many Model F's in the UK and they are starting to fetch high prices in the states -- they are my favourite CO2 rifle although I would dearly like to get my hands on a Howa 55G.
I am not a fan of scopes on pumpers but, if you feel the need, the only way to go (IMO) is the long eye relief scout type like your nice little Weaver -- better still, forget the scope and use a Williams peep sight!