I think we'd only be looking to borrow 2/3 times our income, which I think is ok - this would allow us to look at properties between 5-600k which is what I think we will need and the re-payments look to be similar to what we pay in rent anyway.
Our strategy was to lever up to the max in the knowledge that our incomes would grow into the mortgage. The financing we got was so cheap that it seemed pointless to live in a smaller place than we had to.
Age shouldn't be a problem - we got the Chelsea Building Society to lend us c. 5.2x joint gross income last year, age 21 and 24.