Just mammogram on first breast clinic visit or biopsy too ?

Hello. I have found a lump under my armpit. It is apparently in my Auxiliary (whatever that is) !!! I have my first breast clinic appointment next Saturday and was told to allow 1-3 hours. Is that to allow time for a biopsy, or is that later on in treatment if they think the lump looks dodgy ? Any help/advice would be very much appreciated. Thanks in advance Tina X