2 Answers
No, there are no Oysho stores in London or anywhere else in the UK or Ireland yet.
The closest are across the Channel in France where there are a scattering of branches (11, I think, at the last count).
But Oysho does offer online shopping to UK customers, so if you’re in London and need something from them then that’s the way to go.
Country-by-country statistics on where all Oysho’s stores are, from Inditex, the corporation which owns Oysho (and Zara, Pull Bear and several other brands):
http://www.inditex.com/en/press/information/stores
Oysho Stores