"Sue gets married – that's all I'm going to tell you," Lynch, who tied the knot with psychologist Laura Embry in June, told PEOPLE at BAFTA/LA's Brittania Awards, where Betty White was honored.
"I probably shouldn't have said anything!," added Lynch, who would only say that the TV wedding will take place within the next three or four episodes – and it won't be a big musical blow-out.
Then there's Paltrow’s guest shot: "I did a couple of scenes with Gwyneth. She's got the goods," says Lynch, 50. "She can sing, she can dance. I really was [blown away]. I saw them doing a mash-up of 'Singin' in the Rain' and 'Umbrella,' and they are singing and dancing their hearts out, and Gwyneth is leading them. She's amazing."
As Lynch explained, "She's a substitute teacher for Will [Matthew Morrison]. Will gets the monkey flu and I expose him to it – I turn a sneezing kid on him so that he gets the monkey flu."
The upshot? "So Gwyneth Paltrow is the substitute, and the kids start to all love her. So there's kind of a rivalry between Schue and Gwyneth's character."
As for Sue's relationship with the new sub, "It's friendly – and then, of course, as with all relationships with Sue Sylvester, it turns antagonistic."
Her relationship with Burnett, when the comedy legend appears on the show, turns musical. Burnett will play Sue's Nazi-hunting mother. Says Lynch, an avid Burnett fan: "We sing '[Why, Oh Why, Did I Ever Leave] Ohio' from Wonderful Town, the 1950s musical."