Loopytiles - fair few of these 'scruffy mums' you say in London commuter belt area (which is me, SE London and relatives, East London)?
Well I do get highlights done regularly... and when going to work put the effort in with makeup etc - but on days I WFH - that all goes to pot, I do one aqua fit class a week (just joined gym) and yoga class at work one lunchtime.
My neighbour with 3 kids, 1 under 5, 2 over 5, she gets her hair cut but rarely wears makeup (or very natural) but paints her fingernails. In mum's uniform of padded jacket, sweatshirt, jeans, jogs a lot and swims (with DC).
Other neighbour, highlights, makeup, mixed uniform of jeans, and smarter but she's a photographer (out and about one) so needs clothes that work being out and about, gym member.
Other neighbour works in a bank, so has uniform, also has teenaged DC but no drop off needed and wears makeup and has haircuts, jogs a lot.
SIL - wears makeup but very natural look, brushes hair, smarter clothes - works doing research in British Library but with 7 month old DS not much time or money to get haircut etc no time for gym but jogs and swims.
SIL's SIL (SIL's brother's wife) - works for a major gallery - has 18 month old DD, is naturally trendy/fashion conscious so very groomed and either colours or highlights hair, has it cut, wears makeup but likes red lipstick and earrings, jogs a bit and sometimes gym.
My bitch half sister (yes I said half, I have 2!) whom I'm no contact with - she's a SAHM and a gym bunny, hair is cut short, spends loads on makeup, skincare and I'm sure Botox etc and clothes.
None of the above seriously AFAIK has the money for anything but haircuts, hair colour, maybe eyebrow shape they may go to the beauty salon but I certainly don't and if I do it's to a Moroccan spa for sauna and steam!