Hi Colin
Why complicate the matter?
Two of you are buying, one is putting up the deposit, the other is paying the instalments for a few years while the depositor finishes studying and gets a job.
There is nothing unusual with this. You just say 'purchasing property' so if this is owner occupied that's all there is to it. If it is an investment property, then to the best of my knowledge, any 'loss' can be carried forward by the depositor until she has a taxable income.
If you buy as Joint Tenants, then in the event of the demise of one owner, the full ownership of the property automatically passes to the survivor.
If you buy as Tennants in Common, you will need to write Wills to ensure that the relevant share is distributed as you wish.
Regarding borrowing, it really doesn't matter if only one applicant has an income.
If you want to buy together, then borrow together, it makes for a neater package and ensures that you each have equal benefit, liability, and most importantly, control.
Your friend is right: If it all goes pear shaped then there must have been a clear agreement at the commencement of the project.
Remember that buying with anyone means that for subsequent loan applications, you are responsible for the whole of the debt but entitled to receive only half of the income.
And don't forget - most investment properties start out as 'negatively geared' but within a few years are 'positively geared'. Provided that you intend to stay together then buying together is a good idea. If you have any doubt about this, then possibly borrow the money from her but make a clear agreement about paying her back.
Hope this helps
Kristine