Hi- if you have to ask if you will be overstretching yourselves then you haven't done enough homework! Check out a number of mortgage calculators to see what your potential repayments would be on various mortgage amounts. If they are old calculators take out the mortgage interest relief piece as this is no longer applicable.
For example- say you find a house for 350k, 50k is your deposit so 300k is your mortgage. Repayments over 25 years will be approx. 1600 a month as a very rough figure.
If you have 50k saved, remember that some of this will go to stamp duty, solictor costs, etc.
Typically lenders are providing approximately 4 time joint gross income so your expectations don't seem too high considering you have a substantial deposit.
Good luck!