Tim, I was around at my daughter's house. I thought I would take some photos of the upgrades my electrician did to the meter box and connection to the garage .
The garage now has 50A supply with it's own consumer unit for Zappi and all electrics + provision of solar /battery storage.
He added an additional switch inside the meter box (upto date regs) and further outside MCB protecting the garage
You may also see the CT clamp hardwired back to the Zappi, to control excess demand
I pulled all the armoured cables between the buildings, which was a bloody struggle. Builder used wrong trunking (ribbed) with unnecessary bends and fencing contractor but weight of fence post just ontop.. Job would have been absolute doddle if they had let me lay proper underground trunking before they tarmacked the drive