Cor, how does an ugly bugga like that get a girlfriend

Onya mate, you and that bike look a perfect match.

Regarding the rear brake cable, it is too short. It needs to be long enough to turn the bars fully to each side without binding. You are going to need an inner and an outer cable. If a bike shop assembled her, take her back and ask them to do it properly. On the other hand, brake cables are cheap and easy to install. Take your pick, I'd have a chat with the bike shop first, a nice chat, because they'll often do it on the spot and if you're friendly, you'll be able to watch and learn some stuff.