Well, he didnt have Northdown so im subbing Norther Brewer. Didnt have wy1968, so im going with Thames Valley wy1275,
Ought to be ok I think.
Anything special I ought to know about 1275?
I'm not familiar with 1275, but I've brewed an LP "clone" a number of times. I can't recall if the recipe was in BYO or Zymurgy (maybe both). I've found it a couple of places, and there's pretty much no variation.
Anyway, I think that without using 1968 you won't quite get the Fuller's flavor. But maybe you'll get close enough.
I've also always gone with MO as my base malt.