Quickly wrote this yesterday & posted on another forum in response to a similar question.
Saturday was my first visit to Silverstone this year & it has changed since last year. The bigger , higher stands which give views over the fencing, now seem to be at the southern end of the track.
My comments are based on having access to the stands at the FIA GT1 event.
Luffield - still a small area of the terracing at the entrance to Luffield where you can take shots over the fence. My 500 lens allowed shots at both Brooklands exit & Luffield entrance.
Copse - there seems to be smaller stands at around the old start / finish line than in the past. The result is you can't seem to get shots over the fence anymore. The terrace is only of use if you want to shoot through the fences.
Maggots - from the stand there are good views both of the Maggots / Becketts complex & over to the "new" Village / Loop complex. If you have a front row seat you can get some good shots here with either panning or head on pictures. I used both my 500 & 100-400 lemses here. The 500 allowed shots into Village & the Loop with some fence intrusion.
Hanger straight - there is a small stand on the infield just over the bridge. Decent shots of cars exiting Chapel or on the hanger straight.
Stowe - I didnt get into the stands. However there is a place at the back of the spectator banking where you can take pictures of cars on the apex of Stowe over the top of the fencing. Used my 500 here.
Vale - Small area at vale where the fencing is only 4' high . 100-400 ideal here, slow speed corner lots of bunching under braking.
Club / International straight - I sat in the Grandstand on the straight as near to club as I could get. Good panning shots on the main straight. Also with the 500 I was able to capure cars on the decent from Stowe to Vale, through Vale Then around Club. You are also opposite the presentatiomn podium in the Wing here.
Farm - I sat in the grandstand on the infield at Farm .Good panning shots & the exit of Abbey.
Village / The Loop - the gap in the fencing at Village has now been filled by the extension to the stand at Village. The Village stand is good for shots approaching Village, Village & the Loop.
Wellington Straight - By standing on the road bridge banking you can take shots over the fencing of cars on the wellington straight.
The Wing - at the southern end of the wing there is any area where you can take pictures of cars approaching Vale from Stowe, Vale itself & Club.
I did at lot of walking on Staturday , fortunately the weather was kind.
Some points to remember.
1. There were Not many people about so I did not have to compete for a spot.
2. The rover ticket allowed access into lots, but not all, the grandstands.
3. I was always able to get a good seat in the stands, either on the front row or at the extreme side of the stand.
4.If you are restricted to the standing areas your viewpoints are some restricted unless you shoot through the catch fencing.
I hope this is of use I'm not sure what the access policy is for the Moto GP.