I agree that he didn’t have a plan for 2 primary reasons: Saiyans as a whole are very bad at planning beyond the problem in front of them, and that Toriyama also planned very little of Dragon Ball ahead of time

In universe the explanation I’d give is that while Namek is bigger than Earth it still took Frieza “five minutes” for his blast to actually destroy Namek. Vegeta hadn’t even gone Super Saiyan yet. Even if his blast did connect and destroy the planet (unlikely) he would have had plenty of time to get to a space ship and fuck off

No win, you know… except potentially saving another human’s life