My DH works in events so away a lot. First time he went DS was 5 weeks and at 4am I hadn't eaten tea, and was still in clothes and makeup from the day! Lesson learnt!
My tip is get changed into pjs, make up off etc after tea, so you can just get into bed when you need!
One thing which is positive is that it is a bit easier as there is less mess with less people in the house. Less washing up, less clothes to wash, less tidying etc. I'd recommend having a set pattern as to washing up etc, so I always do it once DS is in bed, so it's clear for the next day. I also tidy, repack change bag, make bottles, etc, so before I relax in the evening I'm all ready to go for the night and next day.
Make sure you have some time planned with friends etc as it can be a bit lonely if you don't see anyone else during the week, but don't plan too much!
If your little one doesn't sleep, work out how to make that easier. We co-slept, not our ideal but DS is a terrible sleeper and I couldn't do all the wake ups on my own with DH away, and when cosleeping at least we get sleep!
It's terrifying at first but you'll find your way, and settle into your own routine together pretty quickly, and it's great as it feels quite an achievement!
We've just had DS2, and DH hasn't been away yet, kind of dreading the first few weeks as we need to work out a new routine with two!!!
Good luck, hope it goes ok and you quickly settle into your new routine etc. x