Unfortunately I don't have an passport, because i never need one for traveling in Europe, so the e-gates aren't possible.

Normally, flights to Stansted don't require a bus to the terminal but a +- 10 minute walk,
I actually prebooked a seat in the plane next the the exit so I can be out of the plane the moment the doors open,
and from the passport control to the bus is something like 5 minutes if I believe correctly.

That leaves 55 minutes for passport control.
If I book fast track, that allow 50 persons per hour right?
any indication on how long that takes then? Shouldn't be more than 30 I guess.
so if that's the case that would give me enough time to get to the bus.

On the regular lines I never had to wait for more than 30 minutes.
But if the Fast Track ensures me in can get to the bus in time I don't mind spending that extra money.