Kate,
I am so sorry to hear about your mum. Please accept my sympathies.
As for the funeral, if people want to raise their eyebrows, let them get on with it and do whatever you feel is right for your mum.
One of the hardest parts of a funeral, I think, is the walking into a church full of people. At the funeral of the father of a friend of mine, the family (including dad) arrived at the church first and met all the mourners at the door. A brave thing for them to do, but it felt right for them. Their father had been a vicar himself, so perhaps he had got the idea from one of his parishoners.