I am a great fan of roasted chicken thighs, with the skin, so crunchy, and the bone in.
Cucumber halves with ham, celery with cream cheese and finely sliced radish, devilled eggs, all good finger food. Sausage and courgette slices - on sticks hot or cold.
Individual sugar free jellies in different colours, done slowly so that one layer is set before the next is added, and the bowls tilted so they are interesting. Individual pieces of frozen fruit are dropped into each new section. Most effective if they can be turned out or made in clear containers, served with cream or real ice cream or cold egg custard. I have to go to a large Tesco to find a full range of sugar free jellies. If they are to be turned out, either add more gelatine or make them up in 2/3rds of a pint of water or they will not hold together.