For sure, in UK as France too or anywhere else, you can find custom board.
About quality, traditional laminate epoxy board are strong enough, once you are not hammering the rails with paddle , shaft or do silly things with the board: just remember: a surfboard is made for surfing in the Ocean water

IMO, excepted beginners's SUP, board won't need so strong construction as BIG compagnies do.
Can be so strong to worth the money they ask for