Anecdotally, I went to watch it on Saturday at 2:30pm and was very surprised at the turnout (and the fact that it still had 4 showings/day at my multiplex). After that, I was hoping for a strong hold this weekend. £2.1m would be very nice!
Having so many spoilers revealed in the trailers actively reduced my enjoyment of the movie, as I spent the first half mentally checking off plot points I knew were going to appear somewhere. I'm going to do my best to avoid the marketing for the third.
It's clear that running against FD would be a big mistake.