Here's what I did:
375 g strong white bread flour
125 g semolina, plus up to another 200 g for dusting
5 g fast dried yeast
10 g salt
400 ml warm water
Olive oil
1. Mix the flour, semolina, yeast salt and water together in a large bowl, then add a good slug of oil. This will be a very wet dough, too wet for kneading. It needs mixing by hand or alternatively with the dough hook of a food mixer for 5 minutes.
2. Put the bowl in a plastic bag to ferment for 3 hours. Every half hour or so remove it from the bag, add a bit more olive oil, smooth it all over and fold the dough over itself a couple of times. Yes it's very sticky at first but it gets easier.
3. Don't have a baking stone or peel, I just sprinkle two baking sheets with a good covering of semolina.
4. Sprinkle the work surface with semolina and turn out the dough onto it. Separate into two equal lumps. Dust everything with semolina. Taking one lump at a time, flatten it and stretch it out into a rectangle. Roll this up into a cylinder four times as long as it is wide and place on the baking sheet to double in size.
5. Heat the oven to maximum.
6. Once risen, put them into the oven quickly, baking at maximum heat for 10 minutes before turning down to 200 ºC for another 15 minutes.
7. Remove from the oven, drizzle a little oil on top and allow to cool on a rack.
The alinsons yeast you have been using is more like brewers yeast than bread yeast and I have also had poor results with it. If your local tesco/sansbury has an in store bakery then you can always ask for some fresh yeast. And moat small local bakerys will sell you a kilo block of yeast if you ask nicely 
