You might not think the Science Museum and the Glyndebourne Opera Festival are a match made in heaven. One is all modern and technology-y and the other is all traditional and art-y-culture-y. But I suspect you've forgotten that the Science Museum has that huge cinema screen – the one they usually do all those 3D screenings on. So what they're doing is showing a live feed from Glyndebourne directly onto the Science Museum's massive screen – which also has 2000 watts of DIGITAL SURROUND SOUND.
Apart from the fact that by attending this event you're weatherproofing your trip to the opera, attending Glyndebourne at the Science Museum also means that you avoid having to travel out to the Lewes-adjacent property which hosts the operas. What you don't lose are Glyndebourne's 'nice' features, like the option to enjoy a picnic with your Britten, or the fact that the performance starts nice and early and has a luxuriously long interval perfect for supping in.
This season the show is The Turn of the Screw, which starts at 18:00 sharp. Regular tickets are £30, Gold tickets, which include a luxury wicker hamper (not sure if you get to keep it) are £45. And the opera's in English, so while I was considering saying 'enjoy your evening' in Italian, I may as well just say it in English. Thought I should warn you this opera is a thriller.