Hard to say.
The Pound litterally scares me.
Every time I have been in London Heathrow and see how expensive electronics are compared to the US.
Even music stores in France, Germany and Portugal.
I saw Ibanez RG570's for 1000 Euros when they are like $560 in the USA.
No wonder Andy said he picked up some gear while he was in San Francisco recording Exodus.
So its hard to say.
Here you might find a used cab for $200-400 and think thats cheap.
$400 USA is close to 200 Pounds so possibly. But then it seems like gear is more expensive there so I might think its gonna be more than 200 pounds for anything decent.
But yes, any cab with V30's will probably be decent.
Crate Blue Voodoo
Randall
Madison
Marshall
Mesa Boogie
Even if you can get a decent used cab and replace the speakers with Vintage 30's.
But the speakers themselves would probably cost you over 200 pounds.