It's not easy, but I've developed some short cuts!
For example, I paint my nails and pluck my eyebrows while watching the children in the bath. Shower, shave legs and hair wash as soon as they're in bed.
Just gone back to work after mat leave, so I have to look "polished" if I can. Hair goes up in a bun. Earrings, perfume, very basic makeup.
On work days I live in simple tailored dresses and smart flats (NOT ballet pumps!) Looks put-together with minimal effort.
On non work days it's skinny jeans (Topshop Jamie or Next cigarette cut) or harem pants (Asos) with a simple T shirt or vest (Topshop, Gap, Warehouse or Oasis, usually). Again, two mins makeup and basic jewellery. Usually not a necklace as DD grabs it while she's feeding. Birkenstocks (brown) as they're comfortable and go with almost everything, or nude sandals (Asos).
I also find a smart-ish jacket makes a difference when I'm going out and about. I have a decent leather jacket and a selection of plain-coloured Jersey blazers (Zara, Miss Selfridge, Oasis) which IMO look much more stylish than the Joules/FatFace prints most mums seem to sport. A plain black Montane waterproof when it's wet.
Also, being almost back to pre-baby weight helps. Still got a bit to go, but I feel much better now my old clothes fit again and there's no overhang. Being back at work helps with this though, as I have time to run to/from the office and at lunchtimes.