+1 to what youngoldbloke says.
When I was looking at getting my road bike, I was quite keen on the Boardman as a way of getting a decent carbon framed bike for my budget. After speaking to the 'Boardman specialist' (a nice enough young student working in his holidays!), I realised that no-one in my local Bikehut was really qualified to advise me. They too baulked at the idea that I might want to ride it round the car park. I was not going to take their word for it that the frame size they happened to have was exactly my size - they just don't inspire confidence.
After I eventually got my road bike (2nd hand). I popped in to ask if they had any Presta dust caps. "Which ones are they then mate? The car sort?"

To be fair, once I pointed to a Presta valve, they did give me two dust caps for free, but would you buy a bike or have it serviced by someone who can't tell a Presta from a Schrader valve?
Then one of the guys at work bought a cheap MTB from them, just to go to and fro from work - and when I saw it the first thing I noticed was that the cones on the rear wheel were loose. I wonder how many other people who are 'new' to cycling or don't know much about bikes end up with brand new bikes that need rebuilding, or are possibly dangerous?
I'm sure that there are some competent mechanics who work for Halfords - but I suspect they are the exception that proves the rule. All the people I've dealt with in Halfords have been nice enough, but just not on the ball. Heaven help us all if Halfords end up putting all our LBSs out of business due to their financial strength. For this reason I never buy motorbike stuff from them either, but the Boardman seemed so good I decided I might make an exception - until they refused to let me ride one. However, probably some branches are better than others. I'd be tempted to get the Boardman but then take it to a proper bike shop to get it set up and checked over, so long as you can make sure you get the right frame size.