Ruby, I just got myself into a routine.
However knackered I am I always get up before DH and shower/wash hair. I have decanted my daily make up into a small make up bag, with just the basics so easy to grab and apply. I found a wonder product in MAC Kohl pencils for a easy, smokey eyeliner which gives a more polished look, but in minimal time.
Hair wise, I love my Babyliss big hair, which has made me feel more groomed in a few mins.
I always get my clothes out the night before, and I have started to get together a bit of a 'wardrobe' for days with DS (I wear a uniform for work). Chino's and jeans are the main stay on my wardrobe, along with stripes, and white tops and blouses. Might be a bit predictable, but I find it easy to pull an outfit together quickly.
Not sure how old your DC's are, but I try to use their bath time to do other things, like eyebrow plucking, paint toenails etc.
I was in a bit of a place of thinking, 'why bother doing my nails etc, when I need to lose a stone'. However, I soon realised that small steps and changes were much easy to take and sustain in the long run.