What's the latest arrival time on Friday?

Hi,

We are going to London on Friday to see Paul Weller at the Albert Hall and want to come straight to Glastonbudget after the concert instead of paying London prices for a hotel. The rest of our party will already be there with tents set up ready. Does anyone know if there is a certain time that we will not be allowed to arrive after or can we arrive any time as long as we've got our tickets?

Thanks