Hi Liftupjoe - Sorry you're going through the mill at the moment. If you have just (by just I mean recently) been refered to the Breast Clinic on the urgent reeferal basis, you should be seen pretty promptly, but within 2 weeks.
When I had a similar referal, the clinic was very through with loads of tests done on that first appointment (exam, mamogramme, ultrasounds, biopsies and so on) with a follow up a few days later.
From there my condition too several weeks to diagnose (rare and atypical - story of my life!), but at all stages I had opportunities to ask any questions I had and lots of information was given to me, so that I felt informed and included in everything that happened.
Good luck at the clinic, and try not to fast-forward too far, in terms of diagnosis. Something like 90% of breast lumps are benign (although of course, that leaves the trroublesome 10%), so try to stay calm until your reality is known.
Fingers crossed for you.