The Last Leg finishes next week anyhow and they've done episodes without crowds for the Paralympics.
Ant and Dec obviously used to working without a crowd on I'm a Celeb. I do think the show would notably suffer (there is a reason they have a crowd) but they could probably throw together hour-long shows for a couple of weeks and rely on Skype features such as Singalong Live and Happiest Minute, plus switch Win the Ads to a call in comp.
Other than those two shows in primetime I don't think there is anything else live with an audience broadcasting at the moment on the main networks at least. The Voice pre-record most their stages so think they'll have a live semi-final and final in April, though that sort of thing could be postponed if necessary a few weeks.
Stay Home. Protect the NHS. Save Lives.