Headaches are a sign of going into ketosis - shouldn't last too long. You'll feel better in a couple of days (at the most).
You can get oatbran and wheatbran from health/organic shops, maybe larger supermarkets too. 1 1/2 tbs oatbran obligatory on attack and 1 tbs of wheatbran (latter is if necessary/wanted - helps with transit probs). Once on phase II (cruise), you must have 2 tbs oatbran daily and the wheatbran amount stays the same. Drinking lots of water will help transit issues too, as will a couple of strong expressos and as much walking as you can.
There's a lot of blurb on the net about the health benefits of both brans, oatbran swells in liquid (so drink something while eating it) and forms a sort of gel which can absorb fat (I believe) so you're not doing yourself any favours in not having it, it's also really nice once you're used to it. Have a wee look at the recipes sticky - there are easy recipes for using both brans - muffins, cake, galette, crumble topping, granola. I prefer mine as porridge (I use the 2 tbs OB and 1 tbs WB with about 200ml skimmed milk - 5 minutes on medium/high in the microwave then add spices and sweetner. Lovely warming start to the day and keeps me full until lunch!
Don't hesitate to join in the forum, everyone's friendly and supportive and I'd not have managed without them - it has made being on a diet so much easier having a group of people going through it with me!
Good luck in your bran search and hope you feel better very soon.