Dr referral to the breast clinic. What will happen at appt?

hi all

i went to gp on monday  who after examination said she could feel mass or thickening 3cm by 2 cm  has referred me to breast clinic said i should here within 3 weeks , she dont think its to concerning as i have discomfort 

on tuesday morning i had a call with thier earlist appointment date on the 8th march 

i asked what would roughly happen, nice lady on the phone said " you will have a mamagram , see consultant same day , and if need any other scan or biopsy also same day " 

so starting to panic little what has gp not told me , is it normal to have extra test same day if needed ?

trying my hardest to stay away from dr google 

got to try stay positive next 4 weeks