>> "For new Office or Azure cloud customers in the UK, no exchange rate can justify any price rise at all".
You are aware that data centres, no matter where they are located, require quite a lot of gear not made in the UK and mostly priced in, or at least with prices based on, USD, yes...?
The price increase percentage being well-above the GBP price collapse is arguable, but it's probably just indicative of what Microsoft expects the future will bring.
Anyway, price increases from foreign service providers is a boon to local service providers, no? Think of it as an opportunity for domestic IT services!