The speaker uses "be going to" in almost all these sentences but he uses present continuous tense in the last sentence. ➡️Why?❓ Because the places he's going to visit on his holiday are intended destinations, where there might be some changes of plan, whereas coming back home can be considered a certainty. Be going to and present continuous.... Can I use these two as I like or something? --> they are very often interchangeable. It all depends on the level of certainty concerning what is being spoken about, in the mind of the speaker or questioner. If in doubt, I would recommend using "going to", which covers the majority (but, obviously, not all!!) 'future' scenarios.