Up to how much of your income would you spend on a mortgage?
To keep your financial life sustainable over the long-term, you should not spend more than 45% of your take home on all your commitments. This includes your mortgage and all other monthly expenses. Think: Home bills, car, work commute, mobile, gym, other subscriptions, ...
You need to ensure you have enough left over to enjoy a reasonable social life, otherwise a property becomes a burden.
The more loans and commitments you have (car lease, credit card debt, ...) the smaller your mortgage commitment should be. If you have no existing debt and plenty of savings left over after you have put down a deposit, you can afford to commit more to a mortgage.
You also need to consider change in interest rates which will increase your monthly mortgage cost. You are likely to start on a fixed mortage for 2- 5 years but after this period your payments can increase. Caculate (or ask your mortgage advisor) how much your payment will increase if the rate increases by 1% - 5%. Whilst a high jump is unlikely in the near-term, it's good to have a range.
With contribution from Ash-Ridge Private Fianance