The formula and procedure in that thread is way too complicated. Look at this E6 recipe, and especially the bleaching and fixing bathes:
- Your Tetenal BX1 is somewhere between 45-50% Ammonium Ferric EDTA, which is referred to as "Ethylenediaminetetraacetic acid·Fe(III)·ammonium·dihydrate" in that link. The recipe lists the solid compound, but calculating how much BX1 you need to match that concentration should be trivial.
- The remaining chemicals most likely likely won't come with BX1 so you have to source them yourselves. Since you appear to be from EU, I suggest Fototechnik Suvatlar (price list here) or Keten. Both vendors have been repeatedly discussed here on APUG, they converse in English so language barriers shouldn't be a problem..
- Looking at the additional chemicals required for bleach, I see KBr (or, even better, NH4Br), Na2-EDTA, Ammonium Nitrate (you can leave that one out).
- As far as fixer is concerned, either mix the one listed in that recipe, or get standard rapid fixer and bump its pH up to 6.60.
- pH matters a lot in E6 processing and if you want to go anywhere near real home brewing, get a pH meter. If all you care about is making bleach and fixer quickly, you should be able to get away with pH indicator paper.