Ok so... I don't know how true this is, but here's what I dug up...
Via BBC-
"Have I got the invite yet? Oh, I've been out of town," responded Dave Grohl when the BBC asked him about the wedding at the Brit Awards last week.
Via The Sun-
The Sun's Bizarre Column exclusively revealed that the Foo Fighters have dropped hints they want to perform at the wedding. Frontman Dave Grohl said: “I’ve saved the date. The performance was good. It’s nice to feel like a wedding band when everyone’s at tables eating tiramisu.” The band, who picked up Best International Group at the Brit Awards 2018, played at Harry’s Invictus Games in 2014.