I know Odeon started opening some of the cinemas at the beginning of July. The majority of them were supposed to open over a two week period with all cinemas open by the end of July. They had a change of heart and this didn't happen. I suspect it was due to Tenet and Mulan etc being further delayed. I have just checked my cinema and it is reopening on Wednesday 26th July for Tenet's release and I imagine the rest of them will be as well. Tickets are already up for advanced booking and they are going nicely
I have found a list of which cinema are currently open and when the ones which are currently closed are planning to reopen if you need to check:
https://help.odeon.co.uk/hc/en-gb/ar...Closed-Cinemas