I can't see that having a mortgage would disqualify you from having a student loan.
If you're named on the mortgage, the lender will either expect or require you to be registered as an owner of the property.
When deciding whether to offer a mortgage, and how much to lend, the lender will need to see evidence of the income of the borrowers to ensure that they can afford the payments -- and when assessing the affordability, they will look at whether you can afford to make the payments with interest rates where they are now, and whether you would be able to afford them if interest rates were to increase.
I think it's very unlikely that they'd count a maintenance loan as "income" -- it's possible, I suppose, that they might allow some part of it, as the loan is intended to pay for accommodation as well as other living expenses -- but it sounds like you're not a student at the moment, just that you might become one in the future, so even receiving a maintenance loan isn't guaranteed.
If you're on a short-term contract, a lender probably won't even take that income into account. They're not going to lend you money on a 25-year term if you only have an income for the next couple of months.
Be aware that if you're named on the mortage with your father and he can't keep up the payments, the lender will come after you for the money irrespective of any agreement you've made with your father as to who will pay.