My mum passed away nearly 2 years ago, during the night in bed (she had been diagnosed with terminal cancer 4 weeks previously). My step dad called me in the morning and I went over to see her, still in bed, and although obviously it wasn't pleasant to see her like that, so cold and lifeless, I stayed with her for about half an hour just talking to her and holding her hand. I had seen her the Saturday before (she passed away on the Tuesday night) and although she wasn't coping with her diagnosis well, I never expected her to deteriorate quite so quickly. I saw her again on Sunday evening as we were called over as she was in a bad way, not eating all day and the paramedics were with her but she was stabilised and seemed "OK". I sat with my my mum for a while after the paramedics had gone, she was in a bad way but obviously I never realised that would be the last time I would see her alive. She wasn't the mum I knew, following the diagnosis she wouldn't get ready anymore and just spent all day in bed and that was really difficult for us to handle. Therefore, seeing her that morning after she had died, so thin and cold, her mouth slightly open from taking her last breath was heart breaking but I'm so glad I was able to spend time with her - it's not how I want to remember her obviously, I want to remember her full of life and love, but there was never any question of not seeing her before the undertakers came. If she had passed in hospital or somewhere else and I had been asked if I wanted to see her in the Chapel of Rest, I would have done so because I would have wanted to say my Goodbyes properly.
It is a personal decision but I would suggest that you go to see her in the Chapel of Rest, it's a very personal time but I'm sure you won't regret doing it.