Hi Miles Dirac,
Firstly, mortgages are based on very individual circumstances and it's not easy to give a focussed response over a web forum, however, there are some aspects which are common in 'most' mortgage applications
The '3 or 3.5' times your salary the providers will lend you is the 'usual' norm - I'd say beware of the places offering 5 or 6 (sometimes more) times your salary as it encourages over lending that could be beyond your means should your circumstances change.
I'm assuming you're American and here for a job. It may be difficult for you to obtain a 'normal' mortgage this way as you have no credit history here. Other's who are in this situation may be able to advise you on other ways of getting a mortage - however one way that I do know of is to put down a substantial deposit (usually 20-25% or more) of the value of the house/property. The lenders are then a little more 'willing' to accomodate you. I guess the higher of a deposit you put down the easier you'll find getting a 'normal' mortgage.
Other ways could be speaking directly to a mortgage broker to see what kind of mortgages are available for 'special circumstances' - you never know, plenty of mortgages have/can be arranged this way.
Another way is if you 'know' someone in the industry/trade - obviously less well known, but nontheless 'available' - Last person I knew retired about 2 years ago, and our current contact only deals in commercial property.
Overall advice, shop around ad talk to as many lenders as possible, dont get discouraged. Definitley stay within your means/level of income and expenditure. Choose an area which allows you to have quite a number of properties within your price range and don't be tempted to increase your lending just to get a place you know is out of your price range.
Property costs in the UK is a real sore point when it comes to finances and day to day living, ask others on this forum what places are like where they are. Pricing levels do vary tremendously in other areas of the UK although the main city/urban areas are getting up to the ridiculous levels like we get in the south east.
Good luck!
Dennis! West London UK!!