In FM do I have to meet the stadium capacity requirements for Football Manager? Because in real life my stadium isn't big enough for Europe and If I get there, will I need an expansion?
Check the competition rules if you can, if it's in the rules, you will need to fulfill it. I have had it before when I've had to have undersoil heating installed, never had a forced expansion though I don't think.
If your stadium doesn't much the requirements your board will take out a loan and the stadium will be upgraded.. If that doesn't happen it's because the rules you are talking about aren't on the game.