[Lord Snooty]

What's happening to those out of contract on the 30th of June? Are they meant to play on till the end of the season?

I think they and the club have the option to do a short term extension to get them to the end of this season.  Thats why Lyle Taylor at Charlton is not playing, he does not want to get injured and miss out on a big transfer so he is out of contract at the end of the month.

Grabara and Simpson have been released, or rather their contracts haven't been extended, so will leave on June 30th.
Elias Kachunga, Jon Gorenc Stankovic, Collin Quaner, Joel Coleman, Demeaco Duhaney, Rekeil Pyke and Ryan Schofield have all extended their contracts into July.
So have loan men Jonas Lossl (Everton), Emile Smith Rowe (Arsenal), Chris Willock (Benfica), Andy King (Leicester City) and Trevoh Chalobah (Chelsea).