I had a look at JuliaWeBWorK, but the lack of tests and docs put me off a little. I also played around with using weave to make sheets, but that’s not quite what I want. I ended up finding Mustache.jl (which I just saw @j_verzani is also involved in, XD). Mustache is pretty much exactly what I was looking for. It’s simple, easy and has everything I need. 
Edit: for symbolic manipulation I found a bunch of packages in pure julia. I’m gonna play with SymEngine.jl for now.