I think £11-12m OW and it could go higher, I wouldn't be surprised if it ends breaking BvS OW which is the highest March opening in the UK.
April will be interesting, I think Fast 8 five day opening will match Fast 7's OW but it'll have worse legs due to Guardians 2 which likely do at least double what the first film did on its OW.
In May I can see Alien Covenant doing decently and Pirates will do well, not sure on OW but I think Disney would be happy with £7-8m OW, I'm not sure if it hit the same heights as the last three films.
Wonder Woman I imagine if it hits the same numbers as MOS and SS, WB will be very happy, I'm surprised they're not opening midweek or Thursday to coincide with the half term but Warner Bros don't tend to do previews with a couple of exceptions.
It's playing in 4DX which seems like an odd choice for a musical film, it can work well with kids film like Lego Batman but I imagine it'll only really pop out with Be Our Guest and the title song.