1. IF only source: perhaps you can have the UK seller simply drop it off at a 3rd party 'pack and ship' that you pay directly.
Here in USA, to buy from reluctant shippers (I don't blame them, it can be intimidating) UPS will received unpacked items and pack and ship to you. You simply pre-arrange an estimate with UPS near seller based on size and weight. I've done it a few times, easy, and UPS is responsible for the item's safe arrival.
2. Is it a simple circle of a uniform thickness? Would a hardwood blank work, i.e. Maple/Cherry ... ___ dia; ____ thick, you then drill for the tonearm? Maple stained black, or you paint it after cutting. If so, I would order two.
I am having my woodworker make bases and 'blank' armboards for TD125's for Steve at VAS. We did two in Cherry, Mahogany will be next.
these are made from maple, 4 optional colors, and one solid Mahogany
https://systems.audiogon.com/systems/9703