Rob, I just watched a YouTube video on terrain modeling and the builder recommended a product you might be aware of? No mention of an odor or allergic issues like super glues so maybe this will also work for you? In the US it's called Locktite, but in the UK it's "No More Nails". Here's a link on Amazon. Cheers.

https://www.amazon.co.uk/s?k=no+more...l_539q07uiqo_p

Edit: He uses this extensively for putting down ground detail; grasses, trees, boulders, etc.