I have been called many times, and served twice. My latest summons was early December. I find it strange that someone from court would tell you you could not be excused, though, with respect, it seems to me that none of the things you mention, though upsetting at the time,could be classed as reason for exemption. I did phone them, because I had submitted a doctor’s letter three years ago, and thought a phone call would suffice, but the lady I spoke to said she could not make the decision to excuse me without a doctor’s letter. The summons which came had loads of information on social distancing, safety precautions etc, and that a packed lunch, masks, sanitisers would be provided. The jurors would be in a cinema in town, with court officials witnesses,accused,only in the court building
I imagine your GP would be happy to give you a letter. You send in your citation, and the doctor sends you the letter.It doesn’t give any information, it just looks like a standard letter.