One possibility is to obtain some Barnes .338 solids or brass-only bullets and then have your lathe-owning friend
custom cut and flatten them to around 195-205 grain projectiles.
Hence, an answer.

Horrors! The British Isles banning lead or lead shot. Next they will pick up the lead ban on water fowl as in the US.
That means tungsten, bismuth or some other bloody non-lead concoction.
Do not forget Hawk Bullets in NJ.
They might consider a limited run of 338 non-lead FP bullets.