I live in the UK does the transformer near the fuse box need to be changed when upgrading from a Ring Doorbell Pro 1 to a 2?
Not if already using a 24V transformer. Both Pro 1 and Pro 2 support 24V AC and 24V DC. The transformer that comes with the Pro 2 is is DC where as they used to be AC. Not an expect on electrics but if not having to worry about powered an existing doorbell or chime then DC transformer is preferable but either will work fine.