Went last year to both the morning and afternoon sessions. You only have access to the pit lane. Thursday morning was quiet although the drives didn’t appear to be coming out purposefully to do autographs as they do in the afternoon. Having said that I got more in the morning than I did in the afternoon, that was just crazy with the number of fans there and was a real bun fight.
I’m going again this year but just in the morning. I preferred watching and meeting team mechanics as they set up. Got close to some bits of kit – front wings etc that were lying around as they made space. Had some great and informative chats with Mclarenmechanics who I think they liked us showing an interest rather than just asking for the drivers.