Going to the job centre

So I have a fit note from my Doctor which has signed me off work till 14th October. Yet the job centre are still forcing me to go into the jobcentre to sign on each week

I thought if you had a fit note you wouldnt need to sign on? I dont understand

Going to the job centre is causing me so much destress, it is a huge trigger for me. I have had a breakdown and meltdown before I have gone both weeks so far