Lithium ion batteries of more than 100Wh, i.e. virtually all ebike batteries, cannot be transported by air for safety reasons. Batteries are categorised as 'dangerous goods' and subject to strict international regulations.
Worth checking with the high speed railways and the channel ferry, if you can spare the time to travel that way, as usually ebikes on trains is no issue, and similar on the ferry.
The Scottish ferries you will need to use are fine. Done that myself. But getting the bike here to start with is a problem.
With a less integrated battery I'd suggest buying a new battery in the UK, and selling before you leave, which is awkward, but maybe cheaper than renting a bike, and leaves you on your own bike for the ride. Not so easy with the D40.
Also, ask Orbea. Perhaps their UK branch if they have one would help you out.