Your thesis won’t be perfect, but typos don’t mean serious consequences. Proofread your thesis as well as you can, but there will probably be some left. You won’t get them all. When you spot them between submission and the viva, underline them in your thesis or make a list.
Your examiners might make a list too; they’ll ask you to correct typos so that your thesis is better, but they don’t ask for corrections as any kind of punishment. Typos can distract a reader, but only a little.
You can’t do much about typos. Find them, if you can; correct them, when you have the chance. They shouldn’t be the focus for your attention. There’s more important things to do.