As someone working in the industry for multiple years now, 50k p.a. is on the low (but common) end, if you're a high performing student, you can probably reach up to 80k p.a. at top companies, but it's much less common.

TBH, unless you're an average student who might not be able to get an internship on their own, I would recommend just enrolling in the regular compsci degree and look for your own internship, otherwise you probably have a good chance at getting placed at a crappy company where you'll probably gain little or out-dated experience. Additionally, I would highly recommend against delaying graduation by a year, you will be far better off having an extra year of full-time experience after you graduate instead of an extra year of internship experience, unless you're a not very competitive candidate, you should think in terms of long-term experience for your career instead of only thinking about having that internship experience for your first job.