I'm doing my last days at my current job this week. I'm beginning a new job next week and am quite affected by impostor syndrome. What happens when they find out how bad I am at programming?

there is never enough sexperience

The horrible thing about being a developer, is that the better you are, the more you see things you don't know anything about and you feel you are a novice.

It's about being honest, humble, keen on learning and teaching. You will be just fine, it will take some time to get into the new team's mindset - but maybe you blow some of their minds too :)

You will be great! If all else fail you can always go back googling.