Getting away with no training plan

[Pkant2002]

Could always do floor presses

[fLux_]

It's not a problem if sometimes you substitute one exercise for another similar movement because all the kit is busy (doing DB bench instead of barbell, or dips instead etc)

As long as you've got a routine and you stick to it as best as you can, changing the exercise isn't going to do you any harm.

A single bench doesn't sound great though...

[Mart001]

I normally ask to share the equipment, problem solved.