Autumn and Peter were private citizens. Peter besides being the son of the Princess Royal, lives a normal life. Their wedding was not televised. And even then, he got heavily criticized because he sold the photos.
Harry is another matter. He is a senior working royal. His wedding will be televised for all to see. There is definite expectations for his wedding.
I am sure they will get some of their personal tastes in there but most likely during things like the reception when it actually will be private. See how well the cake went down. Heck there is even criticism that they used American ink on invitations.
Not that I think she’ll have more than one adult in the bridal party, but HMQ had adult attendants rather than kids. So to say the Brits don’t do that is not true. That’s something that started much later.
——-
As for someone that said at Meghan’s age and this being her second wedding means she shouldn’t have a big bridal party, how do you account for the kids then? They are bridesmaids after all. She’ll have a decent sized bridal party and her age and her prior marriage has nothing to do with it. Her prior marriage is being treated as a non issue here.