I think the first book of
Nabokov’s I ever read was
Invitation to a Beheading which I have in an old Penguin edition somewhere, so it will displayed later. What I do have here and now are three of his masterworks,
Lolita (Corgi 1969),
Despair (Panther 1969) and
Pale Fire (Corgi 1966) in old UK paperbacks.