Depends on your level of debts elsewhere (Credit Card etc...). Once you've been in your job for a few months, you'd be looking at somewhere between:
Mortgage: 3-4x 21k
Deposit: 15-20k
Property Price: 78-104k
But you have to also factor in your repayment method, term of repayment before deciding on affordability. Whatever you borrow, just make sure you're comfortable with the repayments when rates rise and the equity in your property disappears. Although these events are not guaranteed, it's always best to plan for the worst scenario.