I'm near the end I think and not sure if I can go back to do sidequests [SPOILERS]

I'm at the part where Dianamon has merged with Apollomon and you have these constant battles.

Will I be able to do any side quests anymore? I saved before entering the gate just in case, but I'm at Gear Forest now, and just not sure if I'm wasting my time if I just have to reset.

Hope that makes sense!