Matilda without a doubt. I loved the revival of Miss Saigon. Lion King is good to catch on a Sunday because it's one of the only Sunday shows, but I don't know if it's worth replacing anything on your list. Depends on whether you've seen it or not and how much you want to see it.
"What can you expect from a bunch of seitan worshippers?" - Reginald Tresilian
Miss Saigon has a mostly new cast - but Jon Jon Briones stays on as the Engineer and is a performance for the ages. However, the accolades for Imelda Staunton in Gypsy make it a "do not miss" show. Kinky Boots likely will have better UK accents than the Broadway show.
Bend it Like Beckham will have opened - so there will be reviews. Reading about the previews on theatreforum.com suggest the show is getting better and tighter. But, I haven't seen it.
You should also think about plays - in particular The Play That Goes Wrong.
And think about venturing off the West End.
And, most importantly, check out theatremonkey.com for seating and pricing advice as well as information on day tickets.
Great discount on theatre & musicals, definitely worth a look before you buy elsewhere. Always ends up being cheaper than competitors and they have amazing customer service. :)