I suspect there would be a renewal of interest in garden cities (so called), and a rejection of modernism, since it a) emphasises collectivism in everything including housing and transport (no roads for filthy cars) and b) isn't tainted by Italian facism the way the modernist movement is.
I suspect mosely might wobble on this issue though because on the one hand modernism looks great, is economic and matches his socialism in action stuff but on the other, the vast majority of the parties and goverment prefer the garden city. It also fits most british settlements outside of the largest industrial cities the best.
They could go for brutalism I suppose but with britian not destroyed by bombing, I can't see everyone agreeing to demolish everything on purpose and live in a concrete jungle.