Yes, you will be allowed to take out a mortgage with a partner or friend if you choose to live together. You should make sure, if you do so, that you draw up some kind of trust deed giving both of you power of sale so that you are covered in the event of a dispute. You should also decide, and put in writing, whether you'll be joint tenants (sharing the property on a 50/50 basis) or whether you'll be tenants in common, with each owning a different share dependant on your respective incomes.