Do not expect your be allowed to take beautiful photos of the start during the Formula 1 here. During other events at Spa Francorchamps there is a change!
If you want to make pictures during the Formula 1 with the cars on the straight, you have to try it on friday during free practice. The stewards are still very flexible (if you are lucky), and if you ask it kind to them you got a chance.
There are special holes in the fences for the photographers, however, you find yourself also behind a fence. You have to shoot through the fence and through the hole of the photographers.
With a 200mm lens you would still be able to achieve any result, however, a better zoom range is recommended. The cars coming straight at you, so you can freeze the picture.