MikeAqua:
I've personally found that when banks have told me how much we could borrow (based on income, outgoings etc) it was horrifying amount. The banks have been comfortable lending 50% more than I'm comfortable borrowing.
This was also my experience. I worked for 12 years as a corporate financial analyst so I am fortunate enough to be able to build my own financial model with sensitivity analysis in order to make my own assessment of what I can afford. When I used various banks' online calculators the results were highly variable between banks, but most of them appeared likely to be willing to lend substantially more than I believe I can afford.