I don’t know how sensitive to gluten you need to be but there is no difference in the ingredients between GF Huel and non-GF Huel.
The difference is how the raw ingredients are transported. With the GF they are always kept apart from ingredients containing gluten so they are certified as GF.
The non-GF ingredients are not kept apart from ingredients containing gluten so there may be small or trace amounts of gluten that finds its way into the non-GF version. My GF has Coeliac disease and has had the non-GF Huel powder before without issue.
However…