How long should you take off work after a breast biopsy? Or is it better to be busy and take your mind off it?

Personal choice. Going back to work will generally not cause any problems or damage after a (core) breast biopsy. The patient will feel sore, bruised after the local wears off - more so depending on the level of physical activity involved in the job. The psychological part including dealing with possible pain depends largely on the paient. Most take the rest of the day off.
Many centers are. Aaccelerating biopsy to 'read out' times. Many recognize the problem with "presenteeism" being at the desk or counter, ut unable to focus while worryig about the "report". You need to ask "how long wil the report take" and then ask why does it take so long, and ask for the time off of the lag time from biopsy to path report.