Hi,
I know that with Covid nothing is certain and travel at your own risk.
But for those who like to visit Museums and Air Show, the Battle of Britain Memorial Air show 19-21 September is still on with 2 meter social distancing. Dux is the largest Air Museum in Europe(source: their video 
).
I would advise that if you want to go to buy tickets early as they are running out. Also check the UK Entry requirements and transport into the UK. Unless you are a really good swimmer you would need public transport! Booking ahead is imperative as a some ferry routes already sold out as well.
Also many movies were filmed their and their Spitfires als featured in the movie Battle of Britain 1969.
Chewie.