"Actually, i would go to London, England. I would find a nice pub, get drunk, sober up again, then repeat as necessary.
No time to waste on Giles and the nancy tribe."
So yeah i think Spike would go to England to search for Buff, and have a blast doing it too. Quiet why Buffy would go there is another question. I mean spike doesn't yet know she's in Italy does he. Not until the episode "The Girl In Question", does he and Angel find that out.
So being Spike(And an english boozing hooligan to boot), He would search the home country first.
Maybe feeling she would visit whats left of the Watchers Council, or if Giles is there she would visit him.
I dunno, the platinum one is a strange one isn't he. He could even go to visit The Queen, lol.