Hi, and congratulations on the birth of your LO. Sophie was born at 27 weeks due to severe pre eclampsia as well.
I felt exactly the same as you at the beginning - I just didn't know how we were going to deal with the weeks ahead. You do get into a routine of sorts though - I was in hospital for 6 days after she was born, and once I got home, we just got up, got ready and went up to the hospital every day.
As time went on, we realised that it was ok to take time out for us - it does get very intense in NICU and in the beginning there is a limit to what you can actually do. We lived 60 miles from the hospital, and although we really missed Sophie, we started to not visit on Sundays purely because we had to have some time to catch up with things and DH needed a break because he had work Monday-Friday. We did get some friends who lived near the hospital to go and see Sophie on Sundays though, so she still had visitors, and they sent us photos.
My advice would be to do everything you are allowed to do in the way of cares, read to your baby etc, and when LO starts wearing clothes, take them home and wash them yourself so it feels like you're actually doing something "normal" for a mummy to be doing. We really found it helped to focus on the little milestones like weight gain, increases in feeds etc. Also, just take it one day at a time, don't focus too much on the length of time till LO's due date.
As I write this, Sophie, who's now nearly 20 months, is climbing all over me and trying to close my laptop!!
Just give me a shout if you need to talk