What to expect at Breast Clinic appointment?

Hi there.

I am 26 years old and visited my GP last week about a hard lump I found during a self-exam. The GP said it was not a cyst or fatty tissue and has referred me to the Breast Clinic. I have my appointment next week.

I am not sure what to expect, can anyone advise? Will I receive any results on the day or have to wait any longer? 

How long should I expect that I’ll be at the appointment? 

I am understandably nervous.