Sandwich station is the best idea. Put plenty of knives out just for this!
Platter with slices of bread, rolls etc.
Butter.
Things that can be added to jazz up a sandwich, e.g. chutney, mustard, horseradish.
Ready sliced cucumber? Shredded lettuce? I wouldn't put out sliced tomato, personally, as it goes soggy very quickly. I love tomato in a sandwich but only if it was sliced immediately before going on the bread, and it needs plenty of salt and pepper too.
Slices of ham, maybe other meats.
Bowl of egg mayo, maybe with cress already in it.
Bowl of tuna mayo, perhaps with some finely chopped red or spring onion (no sweetcorn for me, it's my least favourite vegetable).
Slices of bog standard Cheddar - I surmise your fussy guests wouldn't be keen on extra mature Cheddar or Wensleydale.
You could still have a separate platter of ready-made fancier sandwiches if you think it's needed. I like the sound of both your ideas, but then if the eaters of Britain were to be lined up in order of fussiness I'd be in the top 100 at the unfussy end. I'll eat almost anything.