Baking chicken while respecting maximum olive oil temperature

That was bad advice. If you're not par-boiling the potatoes they will need at least 40 minutes, but to be honest you are much better off par-boiling.

Pre-heat the oven as before and place a roasting tin in to pre-heat as well.

Cut the potatoes as before, then place them in a large pan of salted water, bring it to the boil, and simmer for 5 minutes. Drain the pan and place it back on the heat for a little while to drive off the moisture in the pan and on the potatoes.

Transfer the potatoes to a bowl and drizzle generously with oil. Season well (you can add spices, smoked paprika is great), mix through, then place in the hot roasting tray and roast for 30-35 minutes.

The boiling process begins to cook and soften the potatoes, and then the dry heat of the oven carries on cooking them while also crisping the outside.

There are some previous questions with good answers like this one, or this that go into much more detail than I'm about to.

You said your bread didn't rise with the first rise, if you don't have a first rise you can't go onto the next step. If your yeast was old, or the temperature was cold in your kitchen or you used cold water in the dough, or the yeast came in contact with salt then its action could have been slowed down drastically and it would take much longer to get a rise. I've had a first rise take up to 4 hours in the past because of these factors. The times given in recipes are just guidelines, you have to be result-driven. Active dry yeast also takes longer than quick yeast to activate. When using active dry instead of quick yeast you would get better results by mixing it with the water before mixing in. I'd recommend using quick yeast as it's milled into smaller grains and you can mix it directly into the flour.

Of course your yeast may have simply been dead, or killed by salt or heat. Get some good fresh yeast and store it in the fridge to keep it fresh long-term.

Also, using all whole wheat flour isn't going to produce anything like a baguette. Whole wheat flour is very heavy compared to white flour and will take longer to rise. A half and half mix would work better. I'd recommend sticking to the recipe first, then gradually modifying it over time until you get your desired result.