Hi
I have experience in running my own business within a Hotel.
Basically you need to go in with a "prosposal" for what you want to do. Arrange a meeting with the Hotel Manager and go through it with him/her.
I paid a set monthly rental for my Beauty room. I paid for my own products & brochures, did my own marketing. You may want to ask if you can add your treatments on to their website if not already on.
I was lucky enough to use their towels, the manager wasn't really there alot of the time so didnt realise that I did that but it saves you alot of laundering costs!
You need to be aware that you will be workin anti social hours all year round if you really want to make the most of this opportunity. I just closed on Xmas day. Guests stay all year round so its not a Monday - Friday, 9-5.30pm job. But the good thing is if you work later one day, you might be able to start/finish earlier the next if its quiet.
Explain to the management how you can bring in more business for them by offering full time beauty hours, you can also do pamper package breaks and offer Wedding make up if guests can marry at the Hotel.
Agreeing on a rent will be the hardest thing, I'd go for a set amount then you have more money coming your way when you are busy. Start low and negotiate higher if the management arent happy. You'll be doing them a favour by offering a full time service for guests. It may be the deciding factor on people booking at the Hotel if they can have a beauty treatment.
Hope this helps. If you need anymore advice, just give me a shout.
xxx