If the smoked oysters are just for me (usually the case) I just eat them as is. Otherwise, perhaps on a thinly sliced veg of some sort, cucumber or kohlrabi, perhaps a bit of cream cheese to “glue” it down. A “prettier” tinned fish nibble (none of them are particular attractive), and maybe available in the UK, are anchovies rolled around a caper; nice on top of a hard cooked egg half, or slice.
Come to think of it, potted meats of various sorts have always been more of a “thing” in Britain than over here, haven’t they? My few older English cookbooks seem to indicate that (including one of my mother’s, specifically aimed at Afternoon Tea). Unless they are so unbearably old fashioned that they aren’t available anymore. I know they are meant for sandwiches, but veg slices or LC crackers could substitute. (Also not hard to make at home if one has the desire)