I don't agree that having a UK service centre will makes things easier - the shipping is as problematic within a country as it is across borders, because often the package will still travel by air. Personally I still don't really understand why it is seen as safer to ship a battery in a device rather than alone, but there you go (perhaps it is because airlines don't want 10 batteries in a box all next to each other).I dont know why you are all blaming YT. Its the LAW you cannot sent naked Li-on batteries in the post. They must be sent in the frame. No different with many Li-on products over certain power capacity.
There are new courier services which offer transport in special containers. But these are not widespread.
This will be the reason for them not allowing battery only returns. This will be much easier when service center is open.