You can get flaxseed (aka linseed) from Tesco or Sainsburys. You can either get it ready milled or whole and grid it yourself. I've heard that buying it whole is better because sometimes the ground stuff goes rancid on the shelf. You can usually find the milled stuff with all the wheat free/ gluten free stuff, or the whole seeds near the ground almond, etc. in the home baking section.
As for the breakfast, if you like smoked salmon, it's lovely rolled with cream cheese inside. I have that for brekkie sometimes. I know some people even have leftovers from the night before.