Gladiators of Hapanu

The Richard Blade novels were a series of adventures featuring the titular character (MI6A's special agent Richard Blade), who was teleported into a random alternate dimension at the beginning of each novel and forced to rely on his wits and strength. Richard Blade was distinctly British, and all the stories are set in England (at least at the beginning and end, with Blade being teleported to some other dimension for the bulk of each tale).