Thanks Gary, yes you are right!, Ring final. Halfway through I did actually consider changing the sockets to radial circuits but I had already told the electrician (installing the consumer unit) I was doing a ring in each room and he was happy with that. It definitely would have saved cable, especially in the workshop! I ended up looping back on myself on each side as I didn't go through all the studs so definitely was not the most efficient use of cable! The Summerhouse side was better, there the sockets are almost a loop anyway so it didn't add too much. Actually still about 5m though! Thanks for the comment.

That's interesting, so why do people do sockets on a loop at-all? I've got a radial circuit in my garage that seems to supply both the lights and the sockets from a fused switch off the house sockets, so was hoping to copy that for my garden building.

Thanks for replying @daibhidhSCO I missed this comment somehow! I would agree @CanOfRabbitHoles a 13amp fused spur will limit what you can plug into you garden room, particularly if you are going to use an electric heater. Mine has its own consumer unit, that is fed from the main consumer unit in the house via a 10mm2 steel wire armoured cable. The sockets in the garden room are on a circuit with a 32amp mcb, then there is a separate circuit for sockets in the workshop, each heater is own its own circuit, there are two external sockets which also each have their own dedicated circuits. All the lights are low watt LEDs and they are on own their own 6amp dedicated circuit. You could use lower than 10mm SWA, and a consumer unit with lower number of ways than mine. You have to think about what you want to use in the garden room, number of sockets, type of heating and lights, then I would advise call a local electrician and have a chat with them. Mine came and had a look and was happy for me to run all the cables myself, connect sockets and lights beforehand, and he did the consumer unit connections in the house and garden room, both the circuits to the MCBs and the SWA, he did it all in about 4 hours. Including testing my work! Thanks!