We're planning on moving soon. A 400k house is still out of my reach. I consider my wages to be an adequate amount, but being the only earner in my family means that we can't set our sights too high. We are in our first house still at the moment. I think realistically you have to ride the housing market. 2 or 3 more moves, and a few years later, who knows we could be in a half million pound house, but it's a big aim for a first time buyer.
People's circumstances are different though. We have 3 kids, so my wife stays home and takes care of them and the house. Another couple might not have kids, and therefore they could both be bringing in a wage, which in turn doubles their buying power.
As for percentage of wages for mortgage. I try to stick with what I was told years ago. 1 weeks pay or a quarter of your monthly salary on monthly mortgage payments. Personally I wouldn't want to be tying up 50% of my salary on a mortgage, especially as interest rates are still very low, and are set to start rising next year. A 1% rise will make a huge difference to your monthly payments.
Just keep your sensible head on when signing up to anything.