If she is putting in 30K you should split the ownership 100/30. Otherwise the 30K could be seen as a gift, but it also good because she intends to buy the house.
If she is renting from you, that isn't a problem, you then are a landlord and should declare the rent as a normal owner, I don't advise the you pretend you live there and it's the rent a room option.
It is not at all clear that she is renting or buying from you? She can of course buy it out, kinda like you are the mortgage bank. You'll have to agree an interest rate.
Having said all that, I think with our solicitor you need to come to a legally binding agreement on exactly what is going on here.
What's the benefit to you of all this, what happens if in 2 years she decides she's off to Oz. By her having an actual share in the house, she is more likely to behave correctly.