Not sure what you mean by A level. Of course you don't need to sound native. But if you cannot communicate you just cannot communicate. I guess it's pretty obvious. Nobody is going to test your English, but if you will make a bad impression and somebody will be worried that it will be an obstacle, then, well they have every reason to act on that worry.

Just do your thing and don't care about making an error here or there. If you know it's a real issue then go fix it, you will have to anyways.