Thats really upsetting that you have to wait until Friday to see your GP, is there any way you could try each morning and see if there are cancellations? Or see another doctor, not your own? or ring reception and explain the situation and go on a 'waiting list'? (not sure how your practice operates) That seems quite a few days to wait for a GP appointment.
Now this probably won't help you much, but I want you to know that the few days of waiting for the GP will be emotionally and psychologically hard and won't affect you physically IF there is anything to worry about. That was what I was told anyway, that conditions benign or non-benign, have more than likely been present for quite a while already before they are noticed and so a few days/weeks here and there won't affect the outcome for you. I'm not sure this making sense, I hope so?
You are doing exactly the right thing to get yourself to the doctor for checking, and although they won't be able to tell you what is causing the breast change, they can then refer you to the breast clinic for further tests. Do ring the helpline that Lizzy talked about below, I certainly did (although I had been diagnosed) as waiting to be checked and not knowing what you have discovered is a horribly anxious time.
You can write your thoughts to us guys on here, there are people who have bc and people who have benign conditions. We are happy to listen and help you as best we can.
So I'm 37 I was in the bath last night and notices a lump on my right nipple about the size of a pea and when I looked closer my nipple has kinda gone in. I've had pain in this breast for some time I'm really quiet scared tried to get in at docs abd earliest they can see me us Friday.