need some advice with year in industry applications / preparation

i thought id wait and see if i could secure one, and then after securing one, make the switch, but i dont know if this is a good idea?

i got the "module" materials online already for like cv help, and intend to use the careers service a lot this year, so idk if i am missing out on much by doing it this way?

The "with year in industry" option that Universities provide is exactly for the reason you described - if you manage to secure yourself an year long internship then it's a simple switch. You literally tell your Uni admin team that you are going to do a year in industry and they'll switch you over and wish you all the best.
It's the same thing the other way around where people enrol onto the courses with "integrated year in industry" from the get go, which confuses people because it implies that you're guaranteed an employment for that year, which is totally not true and if you fail to secure a placement you simply progress to your next year at Uni.
Not sure I understand the question, but you are not going to miss out on anything. The only thing you will miss out on is the experience if you fail to secure a placement, which, especially in software engineering and computer science, could make it more challenging in finding a graduate job for you. Although you can always apply for the same internships after you graduate and then transition into a graduate role within the same company.