Hannah, I am certainly no expert on the law, and I am not absolutely certain of this, but I don't actually think that you need your dad's permission to go to the funerl home to see your Mother one last time. 

I would contact the funeral home and see if you can visit your mum without contacting your dad. We all have our own way of saying goodbye and should be allowed to have the last goodbye if we wish. Your dads is probably going through his own grief but must allow others theirs too. 
take care thinking of you. 
susie

Dear Hannah, Norman wasn't embalmed due to having Covid and there is a fine time line between being able to see the body of your loved one before it's too unpleasant.  My funeral director was wonderful and arranged for me to see him a few days after his death but also advised me that if Norman was not fit to be seen he would tell me as it would be too traumatic for me.  Try and reign your anger in at your Dad as he may know this and is trying to protect you without telling you the truth, we all know how older men can't communicate as well as they should.  I said to you previously that having Norman home was awful for me but the boot was on the other foot, my daughters went home to sleep and I struggled through the night with him, yes I was upset over this but it was their way of coping and I love them and am not angry at them. Try and be a little kinder to yourself and Dad, he is grieving as well, maybe not how you want him too but it was his wife and he is probably like me, lost, alone and coping with so much.  Take care Hannah, love Carol x 

Hannah I hope you are coping a little better since your last post.  Carol x