Yes a stereotactic core biopsy is available on the NHS.
It is relatively fast, but they keep you in for like an hour, they give you a local anesthetic and then remove some breast tissue with a special needle.
My sister had some bleeding in her breast and it was a bit sore, but I think that was unusual, it wasn't too bad she was back at work the next day.
Just to say, she had one because they saw something on her mamogram, her doctor couldn't feel it properly so they did the biopsy, it doesn't necessarily mean cancer

It must be horrible and scary for you with everything going on with you (bless your heart) but don't think the worst just yet.
Hope everything goes well for you, I haven't had it myself but held my sister's hand during hers, so if you have any questions or want to vent, then just let me know x