Help. Home hair dye on decades of salon colour...

[straighttalker]

Hello
I've been getting my hair (naturally ashy blonde, with some grey at my temples over the past year...) lightened at the hairdressers for about fifteen years now. Highlights of creamy blonde and an all over more multitonal blonde.
I'm:
a) sick of having to go to hairdressers every 6-8 weeks for three hours. A very unlikeable ex-boss sat in the chair next to mine last time and we studiously ignored each other (hairdresser - ooh, you've got a lot of tension in your scalp, me (thinking) no bloody kidding)
b) sick of having to pay £150ish every 6-8 weeks (major home renovations ongoing and I need to be very very budget conscious).
c) would like something a bit simpler/lower maintenance

I'm due hairdressers at the moment and so have a good few cms of what looks like very dark roots next to the colour...

I'm contemplating trying a home kit or salon colour at home. Something quite ashy blonde or cool (golden quickly goes brassy in my wavy uncontrollable coarse hair unfortunately). I wouldn't mind trying for an all-over colour initially then maybe a few highlights later if that goes well...

Any suggestions to avoid the incipient disaster, and the embarrassment of having to get my hairdresser to fix it?

Semi permanent or permanent?
All over first then highlights? Roots first?
L'oreal/Garnier/Nice and Easy/something else?

Any advice appreciated. Except don't do it. I really do want to start doing it myself. But as non-disastrously as possible, ideally.

Do you have any local mobile hairdressers? They would be cheaper than salon and will make sure you get the right colour.

Find a cheaper haidresser! I pay a third of what you do.

I used to pay the same as you and it drove me to home colour. It wasn't disastrous on the first one, but after 3 bouts of home lightening my hair was trashed. Colour was awful and A block, I couldn't achieve multi tonal and it was really dry. I had to have it cut really short and start again with it.

Hairdressers are experts in what they do and results can't be replicated at home IMO.

I have a mobile colourist 22 quid for t section every 6 weeks. Comes in, plonks on. Pisses off

Salon near me does cheaper highlights on certain days.
Tbh I'd think whether you want to end up like those women who keep the blonde when try patently aren't a tiny bit blonde any more underneath. It goes green too eventually

I would find a cheaper hair dresser.

Really interesting replies: straighttalker your hair sounds very like mine, although I've been colouring it for twice as long as you and have no idea what it might look like au naturel.

I doubt I'll get much difference in price in local salons. For those who use (or are) mobile hairdressers, are they really good colourists? I always thought that that was a bit of a specialist thing, hence different people colouring and cutting.

mine ie mobile as she found herself too old to cope with all the young twats in city centre salons

I see my hairdresser at a salon but she does mobile outside if it too and she's a brilliant colourist.
she works at the salon part turn because she prefers flexibility of doing mobile on some days so she can fit in things like the gym and seeing her friends. Mobile isn't a reflection on skills levels but try to go on recommendations from people in your area