I am early forties and cool af and I really don’t think Botox and fillers are necessary. And no, you don’t need heels unless you want to look WAG.
However, there is no getting around it - avoiding frumpiness is pretty expensive and much more time consuming.
The easiest no-brainer way of stopping looking frumpy is to stop shopping in frumpy-potential shops and throw out all your clothes from there. Goodbye to anything bought from the supermarket, Gap, M&S, and almost all of the High St.
(Some people can find gem in these shops, I am simply saying the easiest way to avoid frumpiness is to avoid these shops altogether).
Next, do some research and look at Instagram, Pinterest, Grazia, Vogue, WhoWhatWear etc for styles you like.
Spend in cool shops as researched above. Whistles is pretty accessible, as is Comptoir des Cotonniers, Sandro, some Bella Freud, some Toast, some APC, lots of cool younger brands on the Outnet or Coggles etc. This will be expensive, sorry.
For face: get a nice routine going and include eg tan-luxe drops once or twice a week to give you colour. Sort eyebrows, it is a must. Dye lashes. Make up is the last step and by far the least critical.
Hair: Research this when looking for clothes. Also, get a really good hair mask such as the Christophe Robin on. Again £££, sorry.
You have a good figure and good approach,OP. I’m sure you can turn it around, no problem. The initial bit is likely to be quite a chunky outlay for good results though.