Hybrid Bike for commuting

[B4 Sloth]

Am after a bit of advice from those that commute to work by bike.

A few years ago I was massively into my cycling; Time trial, road bikes and other money pits. Owing to injury I was unable to get back into it like I wanted to and ended up selling my bikes. I did have a brief affair with a bianchi roadbike a couple of years ago but again found the bars too low.
I live about 10 miles from work and yesterday cycled on my old Kona mountain bike. It rained. It was cold and I wondered what I was doing. The bikes heavy frame, wheels and tyres make it a million miles from a commuter hack. Changing components is a false economy so methinks I will look into getting a more purpose built bike.
Prefer the idea of a bike built around a road frame than a mtb frame. No suspension. Ideally disc brakes for the crap weather. If I am going to squeeze an new losi 22 into the garage I need to be a bit sensible price wise...so up to £500 i reckon.
Must be able to cope with my lightweigh 15 stone+ frame

Any advice based on personal experiences would be appreciated