The yellow dot is your grandstand.  Having not been to Spa during an F1 meet I’m unsure how they’ll work the flow of people, so you may enter the circuit at La Source, Eau Rouge, Les Combes or if they’re completely mad somewhere down near Stavelot.  But as you have decent tickets, I’d imagine you’ll get in at La Source.

The path around the back of the Eau Rouge/Radillion grandstand will be packed, you just have to gut that bit out.  After that it’s all pretty plain sailing with plenty of space.  Bruxelles is good (also normally a heavy fragrance of herbal cigarettes at this corner….) as you’re looking down on the cars, as is Speakers Corner and Double Gauche.  From Double Gauche (the second toilet block!) you may need to walk back the way you came.  Otherwise it’s follow the path down to the kart track and then back under the main track which will bring you back to Bus Stop.  You’ll need to play that by ear, depending on access/crowds/weather/tiredness!

The green dots are the interesting places to view, the green line is the path that runs around the circuit.  It is possible to walk all the way round, but again, I’m unsure if that is possible during F1.