I'm Home Counties and got a 'top' salon in a middle class market town (can't think of a better description.)
A half-head of highlights is around £95, and a cut/ wash/dry is £75-ish.
This is with a long-term snr stylist.
I used to manage a whole year between highlights (I'm a mousy blonde, used to be more auburn blonde.)
Now, my hair is 50% grey and I find the parting area shows the grey in a few weeks. I've also swapped to a slightly warmer blonde highlights, as the pale gold were washing me out.
so with a bit of help from a colour wand (powder) I can only go 3- 4 months between cut/ colour.
I've never spent this on my hair EVER.
So it's working out at close to £200 every 3-4 months.