I had a super small wedding - 6 guests in a registry office followed by brunch in a nice local cafe and a cake. Didn't bother telling anyone else about it until after. Total cost was £147 not including our brunch which my mum paid for.
It was my perfect day, I wouldn't have wanted anything else. Our mums made a bit of a fuss and asked us if we'd have a party at least so other family members and friends could come and we said no. It just wasn't what we wanted.
I've been to lots of friends weddings, some of which cost upwards of £30k and they've been lovely days but all our friends have said afterwards they didn't really experience it and wished they'd done something smaller
just do what feels right for you and your partner