I've bought, traded and sold hundreds of instruments all over the world in the last 3 decades. My last buy, a Noguera Yves Carbonne Signature 8 Fretless was bought from an Italian guy living in Ireland, but the bass was still in Italy. After the usual tractations, the bass was sent through a packaging center near the brother's seller place who was in charge of the bass. Everything went smooth and easy. It was a more than 3.000 Euros bank transfer to the seller account who is not even a BassChat member.
The insurance is simply mandatory each time and doesn't cost that much, depending on the the insured value and the courier, it can vary from 15.50 Euros using the post of Luxembourg (for 3750 Euros really insured) to more than 100 Euros using the leader couriers which are not always the best choices.
Investigate a lot before buying and ask for specific photos... Don't hesitate to ask for feedback too.
I'm not an overconfident guy, so I do this with great care.
Ok, l'm not in the UK, but in Belgium. Check my feedback if you want, Dave. 😉