Like most officers in most branches Signal Officers have a variety of tasks depending, especially, on where they are posted.
Sometimes a junior Sig O may have to make decisions (judgement calls) about how best to deploy and use bits and pieces of technical equipment. As a general rule (s)he will decide and soldiers will execute.
The duties of a junior officer in a field unit are quite different from those of, say, a major or lieutenant colonel in an engineering branch in HQ, but one must have been the former before being the latter.
Your degree might matter, especially if you want to work in some of the rather specialized areas. In my opinion (which is worth exactly what you are paying for it) degrees in Mathematics, Physics and Engineering Physics are the best for overall value and flexibility, next Electrical Engineering and then all the others.
I'm guessing that Signals will tell you that Computer Science is a highly desirable programme but I suspect they are wrong. My sense of how the world is evolving is that much of the work currently done by computer scientists and engineers will devolve to technicians or become the domain of a handful of folks with PhDs with little room in the middle for technology managers.
Let me give you a couple of examples: the current VCDS, LGen Guy Thibault is a Sig O, his first degree is in Math & Physics; and Gen (Ret'd) Ramsey Withers was CDS, he was also a Sig O, his degree is in Electrical Engineering (awarded by Queens because, back in the old, old days RMC did not award degrees). Your degree should teach you two things: how to think, and something, a bit, about one (or more) areas of interest. Signals, like every branch of the CF, has a need for thinkers and for men and women who can act - do the right thing and do things right - in difficult circumstances.