I'm looking at getting a new bike to replace my current hardtail mtb for commuting about 8 miles a day, plus possible train travel, and longer commutes elsewhere. 

With a budget of under £400, do I go for a mid range singlespeed/fixie with a flip flop hub, and just man up and struggle through the hills, or get a bottom/low range road bike, risk it getting stolen/trampled/damaged, but have the ability to go on longer rides (which doesn't really interest me, but will still happen occasionally). 

As I see it, a singlespeed is less flashy, so therefore will not attract as much attention with regard to theft, and although would be a struggle on longer pleasure rides, will outweigh the benefits of a road bike with gears?