Do oat flakes (Spar S-budget) contain gluten

Dextrose is another name for the sugar glucose. In the US most powdered dextrose and/or glucose syrups are produced from corn starch, in the UK and other European countries they may be made from wheat or other starchy plant sources. According to a 2008 study from Finland, even though wheat based glucose syrup was found to contain low amounts of residual gluten, it was tolerated without harmful effect by people with celiac disease.

Though the ham is not likely advertised as "gluten free", even if there was gluten in the dextrose, the final concentration of gluten in the ham would likely be well below the 20ppm concentration to qualify as such according to the FDA rules.

Pasta relies on gluten development for its strength and structure. Only wheat and its close relatives have the necessary precursor proteins, glutenin and gliadin, from which gluten is formed.

You simply will not be able to make pasta from 100% oat flour using a recipe designed for wheat flour, as oats do not contain gluten (well, technically, its precursors).

If you desire a gluten free pasta, you should search for recipes specifically for that purpose. They are often bound together with xantham gum or other hydrocolloids.

If you are just looking for an interesting pasta as an alternative to the more traditional ones, you need to make sure you have enough gluten available to support the structure (and overcome the weakening that will come from using oat flour, which will physically interrupt the gluten strands). I would suggest making sure you are using high protein wheat flour (such as bread flour), and only substituting a portion (no more than say 25%, and you might want to start with smaller amounts to see how it works) with oat flour. I haven't tried this, so you will need to experiment to find a good balance between oat flavor, and the ability for the pasta to hold its shape and structure.