Could not agree more with AcidPerm about the importance of getting advice and a contract for a partnership agreement. Another point to consider is if you trade as one company you will be liable for Vat once your combined turnover hits £85k. It you stay as independents with a business arrangement splitting bills you can each take £85k before registering for VAT.
Regarding utility bills it really depends on how large and insulated your space is. If you have a large glass window and lots of people coming in and out it will cost you more to heat and cool the space.
Your water heating will depend on how much hair washing and rinsing you do and how you dry hair. There is an eco aware training scheme set up by Prof Denise Baden of Southampton University. Adopting the changes identified in the Sustainable Salon Certification saves the average four-seat salon 286,000 litres of water, 24150 kWh of energy and £5,300 a year. Note the phrase "save" it suggests that salons spend quite a bit on their utility bills. The training is online, free and only takes a few hours and gives you plenty of food for thought.
For an information overview see here
https://esrc.ukri.org/news-events-a...ting-carbon-footprints-in-the-service-sector/
And the training and certification is
https://ecohairandbeauty.com
And there's an interesting ted talk here
I don't do hair so I can't really help - we get through 2-3 loo rolls a week and our water bill is £18.50 a month. I've worked really hard to get our heating bills down with insulation and Eco infrared heating but we still spend £250 a month in winter and about £100/£150 in summer depending on how many cooling fans we switch on. This doesn't include heating water for hair washing which is the biggest cost.
i use far infrared heating panels in my salon which are the cheapest solution for me, I believe you can get infrared water heaters as well. At present gas is by far the cheapest form of heating but that is likely to change as the electricity grid supply is getting cleaner and pricing reflects pollution costs as well as supply costs.
My salon gets uncomfortably hot in heatwaves because we face the morning sun and have a large glass window. I'm looking into fitting blinds or awnings to reduce the hear and it turns out that we also benefit from "free" solar heating in the cold months of the year so I need a summer only shading option, not a blot the sun out all year round option.
Lots to think about. If either of you are working in a salon at present, discreetly read the electricity meters every week. If you do some sums on energy consumption and number of chairs you should get at least some feel of costs. Electricity is around 25p per kilowatt.
Hope this is helpful. Good luck