Had breast biopsy today - have been told it's most likely cancer

Found a breast lump last week, which felt quite large. GP confirmed and I was referred to the breast clinic. First appointment was 3 weeks from initial GP appointment but i rang and got lucky and had the appointment today. It was a whirlwind of tests: mammogram,  ultrasound and biopsies. It's a hard mobile lump of 2.5 cm (initially thought to be 5cm) but no lymph node swelling felt.

Noone can say until the biopsy result are in but i was told it is likely to be cancer. Subsequent conversations were all positive regarding treatment and prognosis and I  feel fortunate that all these were in the same day and so quick.

Then i got the next appointment sent to me not long after getting home, which wasn't expected and I've  read up a bit, which is terrifying.

I go from dealing with it to panicking, and feeling like I'm going slightly mad with worry.  I know different parts of the country have different pathways. Interested to hear of other experiences and any advice on what to do or how to cope would be greatly appreciated.