The website actually states:
Whilst an FAC is not required to purchase these heads, we have been asked by GMP to request proof of a license prior to sale for a small number of pistol calibers; .25, .32, 9mm Makarov & 9mm Browning
So no mention of .38 special.
Also £16.75 for 100 isnt cheap when Shellhouse bullet co are just over £30 for 500