I unfortunately won't have my grandmother with me when I get married as I lost her last year so I understand how terribly upset you must be, I am getting married in 5 weeks. Luckily your grandma is still here so you should cherish this time and I think sending her a bouquet of your flowers is a lovely thought, my grandma would have been thrilled with that idea, its simply lovely. I'm using my grans wedding ring.
Can anyone from the care home bring her just for the ceremony? If not, have any of the carers where she is have an iphone so you can facetime your gran and keep it running so she can see everything that is happening?
I hope you find something to make you feel happy and provides you and your gran with special memories xxxx