I was at the FIAWEC race there in September. As a photographer I did struggle a bit, particularly in the GA areas - a lot of very high fencing.
There is not a huge amount of space at the top of T1, but head round to the inside of T2 for a good view. The area around the twisty bits will be good too as you can see across to the Turn 15 area as well and it looked like they were setting up big screens around this section.
For future reference, the main grandstand is a complete no-no. Not only can you not see anything but the pit road, the front row of the upper section was partly submerged and crawling with massive bugs (this was taken later on when there were less!) which didn't seem to affect the other grandstands. The T1 grandstand is good, get as high and far to the top of the hill as you can for a commanding view of the home straight and T1 into T2. The T15 grandstand is probably the best, at the end of the back straight and with a very good corner complex. They did seem to be putting up more small stands for the F1, we stood on the T2 grandstand for a bit before being ushered along, seemed to be a pretty decent, if rather restricted view.
If you can choose parking, section T was a good choice - you access it by driving past the main entrance and continuing up the hill, hard to find first time around, but the big plus is that you exit separately to the main crowd and the police are controlling the traffic, so we got out pretty easily.
As a (relative) local, I'm sure you know what to expect weather-wise. The rainstorm that hit the 6 Hour race was unbelievable and obviously the terrain was very muddy - bring boots.