If you can't go, you can buy flowers online, but you can deliver them to your door. I don't know if the cake is ok, you should also send some birthday presents. I think you can write her a love letter. Wow, she will be very touched. Your feelings will heat up. Oh, blessings ~ ~
As for your supplementary question, when is your birthday, of course? You can send her a message to wish her a happy birthday at1midnight on October 4th 12: 00, but if the official birthday is to be celebrated during the day or evening on the fifth day, your gift is enough for him to arrive on the fifth day.