I asked my wife for a bottle of Jazz YSL for Valentines and she said she went to several stores where it was out of stock and the major perfume/cologne store she visited said it was now discontinued.
I don't know about in UK, but here in Los Angeles, YSL has a weird distribution network. A lot of their scents are not available in major stores.
I get my Rive Gauche Pour Homme from the YSL store.
I see plenty of it available online. Basenotes doesn't note it as discontinued, but I don't think they carry it at the YSL store I go to. Hard to say. Bet there's still a lot of to be bought out there.