I'm sorry to hear that sad news. Please do try to speak at the funeral service, it will help you to process your grief.

Even if you don't believe you can, take your notes or just speak freely about your Grandmother. I'm sure there will be points you make that others will appreciate also.
It is sad she passed before you were able to get to her, but also you most likely have a happy memory as your final time you saw/talked with her, so maybe that is better, I cannot know.

If possible have someone recording the service as well, while you may not want to see it now...you may in the future after your process of grieving is over. Others may also appreciate this record also at a later date.
Again condolences for your loss.