Mini :
Speed brake at 180IAS is about as useful as an ashtray on a motorbike, you would get around 1000fpm from memory, weight would play a big part.
You don't get full speedbrake with A/P engaged, only 1/2.
If you are in the sim doing a check I would advise being conservative enough to not be in the position of needing speed brake with flap, this is usually the domain of real world cock ups ( most of my approaches ) or heavy 321s.
We don't have " std weights " for sim, one PC might be at 50 odd tonnes, the next at 70 odd. ( An interview check would probably be at a mid weight, low 60s )