don't go on your male friends, they may be same height but they may have shorter legs, go on your own measurements. they normally go on leg measurement first, and then if you have a shorter reach, you can choose a shorter stem.
i'm 6ft so never had a choice of getting a women's specific, as a lady has already pointed out on here that they stop at 5' 10, but going on overall height is complete bollox, i know people my height with a 33 inch leg and i've got a 36 inch leg, so it's really all down to your own measurements.
you will feel more stretch out on a road bike than one with straight handlebars, because that's the nature of the bike, but the shop will advise if you are reaching too far. my stem is half the length of the one that came on the bike so there is quite a lot to play with there. saddle position also helps to make sure your knee is correctly position over your foot/toe. the main thing is to get the frame size right first, and then they can tweak all the bits after to make it a more comfy ride. but as you've discovered, you can tweak the bike as much as you like, but if the frame size isn't right, the bike will never be right. so you must get the foundation right!
if
Halfords are willing to give you your money back, although i am a fan of Boardman, i would be tempted to just get my money back and go to a good LBS. Sounds like your Halfords staff are not very good.