I know if you can get the company to mark the item as a sample then you shouldn’t get charged any import charges. I’ve had companies write in like paint pen on the items - ’ sample not for re-sale or production’ - and put the same on the invoice so when you go to customs you can open up the item and show them that its marked so no import costs is needed. I know its for ireland but I’m sure UK has similar as Irl has taken most laws from UK or Other EU countries: Permanent importation of samples
Worked for me on previous hobby projects about a year ago - not gotten around to buying my efoil gear yet.