Basically, borrowing more than about 3x your gross income is fairly risky. Many lenders will refuse to loan much above 3.5x. Some will go up to 4 - 4.5x. But good luck going any higher.
What that means, is that if you were earning 50k, had a fantastic credit record, absolutely zero other debt [no car payments, no HP, no credit cards/store cards with balance on them], and wanted to buy a $400 k place - you'd be looking at a minimum cash down payment of $200k.
Any other loans will count against you, and limit the total you will be able to borrow. Then you've got insurance (life assurance, buildings insurance, contents insurance), taxes, other fees, etc. to think about.
With a $200k repayment loan - you'd be looking at $1300 a month of non-negotaible expense. Of course, an interest only loan would be cheaper, but carries the risk of being saddled with a large debt that you cannot pay off at the end of the term - in the worst case scenario, you may be unable to pay off the loan, even if you sell the property.
$1300 should be manageable, but could potentially leave you with a shortfall, if you need to perform maintenance on the building, replace your car, get made redundant, etc. You do need to consider these possiblities and how you would fund them before taking on such a committment.