Unfortunately PPL training is run as an intensive '45hr' course so they drop you in at the deep end, making you do the radio early on. It's easy to get a total brain overload.
IF a private pilot cannot answer the radio in a reasonable manner, they absolutely do NOT belong at the pointy end...fact.
Learn and learn some more, that is the key.
Have a problem with the ATC communications?
There are many internest sources, learn and be prepared.
NO excuse, whatsoever.
Period!