
@Spevna - Hmmm. How about this, where troops are compulsory (i.e. Mission 2), take your compulsory spannerboyz. Where troops are optional, it's up to you if you want to take them. Just don't forget that depending on game results, some minis may not be available to you as they go into your Mission 3 reserves.
@All - Same goes for any other compulsory units (mainly FW lists I guess), if that slot is compulsory for the mission, take your compulsory unit. If it isn't, don't worry about it.
While we are on the subject, if you need unit A to change unit B's type and you can't take unit A, you can't take unit B with it's alternative unit type. (E.g. Marine Bikes are Fast Attack, but can be Troops if you have a bike mounted HQ. Mission 1 doesn't allow HQ's, so you can't take Marine Bikes as troops.