Canapés

Depends on your timings as you may not need them. If your ceremony to food time gap is a 2-3 hours i wouldn't bother, just have drinks. What time is your ceremony? Most people tend to have a big meal before either breakfast or lunch depending on the ceremony time. Other alternatives could be snack bags you make yourself, we did that and had crisps, biscuits, sweets, nuts etc but our guests were travelling between venues so took them with them, venues probably wont allow external food bought in.

I think they are 100% worth it. Unless your meal is immediately after the ceremony, or your ceremony is 3pm onwards, people will be peckish and will have started drinking. If canapes don't come round I always notice the conversation erring too "are there any snacks? is the meal soon?" and at least one person gets too drunk on an empty stomach. When they do come round, people are always delighted and it just makes for a great vibe because guests are happy.

If you don't want to do proper canapes, why not ask your venue if you could provide your own - get picnic stuff in from Sainsbury's (or M&S if you want to be fancy haha) like mini sausage rolls, mini scotch eggs, mini pork pies, bowls of crisps...?