Perhaps those are used in some regions, but as far as I know, they don't seem right.
"Let's go inside" doesn't quite make sense since you are already inside. (I think you are trying to say let's go to the center. Read below.)
"Let's go further" could make sense if you're already moving towards a particular section. As an initial command, it doesn't make sense.
"Let's go to the center of the coach" could work if standing in the "center" doesn't block exiting passengers.
I would say
- Let's step/move aside.
- Let's get/move out of the way.
- Let's go/move to the [location].
- Let's go/move further to the [location].
where the [location] is a place that does not block the exiting passengers, like the back/front/center/etc. You can use 4 when your initial movement was insufficient. To the [location] is optional in 4, since the location should be clear from context.