If you are a trousers person, you may feel uncomfortable in a dress which could require you to wear heels too.
However, that coat is lovely and you could wear boots if you wanted to.
I did go to a winter wedding where the bride wore a long cream dress covered by a cream velvet cloak with a large hood; it did look beautiful and unusual, but she was a bit younger (50s) and carried it off well.
Adverts that are being shown on the tele
When a political leader lies on their CV - can you trust them?
look, Warmthlover. It is the right time of year to wear something long and lush - dress & coat, tights and long or ankle boots. No patterned or lacy tops, but maybe a bold colour, whatever happens to suit you, with a beautiful, fur-trimmed hat. The groom could wear a tie to match the bold colour of your outfit. Many congratulations and please let us know what you decide. (Incidentally, I work in a charity shop and there are bargains to be had. Also, you can return them if you change your mind within 14 days, they are then held for 72 hours before being steamed and hung in the shop.)