Most of the timings all look about right - you could maybe knock 5 mins of the brow shape and tint, but it sounds as though these are the timings that she needs to deliver excellent client satisfaction.
You need to spend some management time understanding the beauty side of the business: timings, costs, premium services, clean up. Look at what treatments are booked as combined hair and beauty visits. Are clients mostly coming in for the works - brows, hair, lashes, nails all on the same day? Or is your beauty service running independently? It's important to understand. Go through the bookings carefully, maybe start by analysing the lash services.
You should have an express lash service which lasts up to 2 weeks, no infills with this service and try and get this down to 45 mins max. Then individuals at 90 mins and Russian at 120 mins. Infills with both of these services.
Change the way you offer lash services. A lot of lash techs make their money with infills. Only infill your own work, not another salon. Offer a 30 min infill service for £25 if they return within 2 weeks. Charge almost as much as a full set for more than 2 weeks (maybe discount by £5) booking a maximum of 45 mins and refuse to accept bookings for infills after 22days. Design a lash treatment menu which explains about aftercare and your lash services.
Tell clients you never expect them to book in for a full set unless they've had a break in wearing extensions. Explain that you heavily discount the cost of the initial set because you make your money on returning services - and only offer full sets of lashes on off peak days/times. Reserve your peak demand times for infills and tell your clients that you are very sorry that they didn't rebook for infills when they needed to, but unfortunately you can't afford to disappoint 4 clients needing lash infills because you are doing a full set.
I always book an hour for LVL even though I'm very experienced. It gives me the results that clients return for and I charge more than other salons. And I sell an aftercare serum. Lash lifting in theory works very well with hair because it's a treatment with a 6-8 week return time, just like hair services. You could try offering a hair and lash lift promotion which matches your existing lash lifting price and add £10 to your standalone lash lift service. Make sure all your hairdressers have lash lifts - and can talk about these services. Run the promotion for 3 weeks and count up how many new clients you introduced to lash lifting - and how many regular lash lifting clients booked in for hair. (You don't want to get just lifted lashes wet, hot, or steamy so this needs careful discussion as a team).
With spray tan I assume this includes clean up time - talk to her about maybe only booking spray tans on particular days and trying to book 2-3 spray tans back to back to benefit from efficiencies. Spray tanning doesn't work well with other services so maybe push this into low demand times/days. Or have dynamic pricing - charge more on some days/times.
Regarding her pay - you are drastically underpaying her and you need to address this or risk losing her. You need to look at what you can offer to make her feel valued. Free hair colour, cut and blow dry every 6 weeks? Professional hair care products bought at cost price?
Moving forward, everyone looks at their actual hourly pay. If you can't afford to pay her more money per hour you need to cut her hours to fund a pay rise. If I've done my sums right you should be able to pay her £7.70 per hour for a 30 hour week without increasing your salary cost. Set her a target. Tell her that when she hits this as a minimum for 6 weeks in a row, you'll add 2 hours.
I've recently decided not to fill a vacancy. I spoke to my team and said that there would be more hours for those that wanted more hours and more pay for those who wanted more responsibility. I had some staff who didn't want more hours and weren't able to justify a pay increase. I need them to be more flexible with their hours and more productive. I've had to find other ways to incentivise them - free massage and free training from me has worked very well. It's cost me bookable hours, but has saved me management heartache.