You must do a Bedikah before you leave to Eretz Yisrael, before Purim without a bracha. After the Bedikah you should say Kol Chamira of the night.
Explanation:
The Gemara Pesachim 6a writes : Rav Yehuda in the name of Rav said one who leaves with a caravan before thirty days before Pesach doesn’t to need to do bedikah. During thirty days ahs to. Abaye said within thirty days is only if he intends to come back other house before pesach but if not then he doesn’t’ Rava said to him if he pals to return before Pesach even from Rosh Hashanah he doesn’t have to. Rava says before thirty days is only if he doesn’t plan on returning at all, but he plans on returning before Pesach he must do a Bedikah.
The Rishonim argue what it means ‘planning to return’:
Rashi and the Talmidei Haramban and the Ritva and Mahram Chalava explain that if he plans on returning during Chol HaMoed then he must destroy all chametz before he leaves so when he returns there won’t be any chametz. Not planning to return is that he won’t plan to return at all during Pesach. Dn eh does need to do a bedikah.
The Ittur, Semak, and Rambam all say that planning on returning before Pesach or during then he must check before he leaves, maybe he will be delayed and will return without time to check, He doesn’t plan on returning means until after Pesach.
The Shulchan Aruch OH 435:1 writes. One who goes on a long journey and no one is home to do a Bedikah. Within thirty days he must check (Rema without a bracha). Before thirty days he doesn’t have to (Rema when Peach comes, he should do Biur). If he plans on return gin before Pesach then he should do a Bedikah and then leave because maybe he will get delayed and come back Erev Pesach and it will be too late to check.
Shulchan Aruch 435:2 some say because thirty is only if he does not plan to come during Pesach and even if he wants to arrive before or after Pesach, he doesn’t need to do a Bedikah since it is before thirty days but if he plans on returning during Pesach even from Rosh Hashana, he should just check.
The Mishna Berura rules that many Poskim are stringent like the first opinion, however if he has no time he can rely on the last opinion and he doesn’t not need to check unless she plans to come on Pesach.
Lehalacha if you leave before thirty days and you plan to come back before Pesach you should do a bedikah before you leave.
There is machloket if you go on short trip. The Maharam Chalava, that even if you come back 25 days before Pesach you must check . so, if you are going on a short trip you also must check.
Rabbeinu Dovid on Pesachim understood that this is only if they are going on a long journey. However, short trip he doesn’t the to check an so rules the Mishna Berura 436:2.
The Or Letziyon ruled that since today there is good transportation it is only far if he goes to Chul but to go to a different city is close and you don’t have to check.
The Rema writes that you should not make a bracha however some say that during thirty days you must make a bracha even before the fourteenth. The Shar Hatziyon rules that before the journey you should make any bracha and so ruled R SZ Auerbach.
The bitul is a good idea to say in case you forget to do if you are travellingt.