I have the same issue with work clothes. I bought two pairs of black wide leg trousers which I wear on repeat.
Cream looks terrible on me so I can't do cream and black, I have to hunt down oatmeal and beige which is tricky online.
I did find a few bright navy things in kettlewell and sainsburys - roll necks and v necks for work, and some beige jumpers and cardigans in m&s. Also have jumpers in some of the lighter colours like peach and hyacinth - the marks and spencer supersoft jumpers are great. They do them in tomato red, blue, coral, peach and shell pink.
Dove grey is a good neutral but hard to find grey that is clear and not heathered. My compromise is a pewter grey, as my hair is dark rich brown it kind of works.
White looks good but black and white on its own is a bit cold. Terracotta was a 25% colour but that's quite a good work colour. I'm not averse to burgundy as it goes quite well with hyacinth and is a cross over colour. I've kept some things in aubergine that I had. Aquamarine is also quite professional, I have a nice blazer from M&S.
Couldn't find chocolate brown for ages, only bitter browns, except for a pashmina in mango. I also don't know how to wear brown. It was a 100% colour for me.
Like you say the key is to browse from now into spring (just the time I don't feel like spending!). I had my colours done in an October so it was a long wait and many incorrect jewel tones purchased!
In the beginning I was buying anything I saw in my colours, or if there was an event I'd look for a green dress for example. I pared my wardrobe right back and got rid of loads. It saves so much time in shops too.
This year I'm going to train my eye to buy more good quality neutrals. I'd love to have an outfit head to toe in the main neutrals. I'll probably have completed that by the time I reach retirement age 😄
Plus probably need a couple of black v neck dresses.
I haven't bought anything for a couple of years or thought about my colours but I've been going through my wardrobe the last couple of days hence the essay. : D
What was your worst colour? Mine was sunflower yellow. Looks great very very far away from my face. The autumn gold / ochre was nicer but my consultant didn't agree.