UK answeres preferred; going to a wedding in January. Would any of these ideas be suitable to wear?

I think that's tricky because it's likely to be cold for the ceremony so you would need to wrap up but the reception sounds like a formal evening event. What about something like a simple plain wool dress worn with sparkly jewellery and perhaps a fake fur wrap? Autograph at Marks & Spencer have a simple but lovely velvet dress which would be perfect.