Break the skill down.
Even if you can do the lead ups, when you come to the blocked point, go back and "review."
First skill: forward roll (see, you can front tumble!)
Then, dive forward roll from stand (small jump onto hands, support on hands, then roll)
Small run, punch dive forward roll onto resi or mats or wherever punch front attempt will be shortly performed.
Same thing with more rotation=likely not quite right front tuck, but past the first hurdle of attempting it anyway
I know in a non-open gym situation you can't usually set up a mat stack (which would be ideal to do the punch dive roll up to) but for most of this you should be able to "warm up" on the side and I'd guess the coach would be okay with these lead ups, just let them know you are having problems trying the punch front.