Thought I'd contribute to this thread seeing as I took two languages in my first year of Arts. My two were French and Spanish (advanced).
As far as the workload was concerned, French for me was the most difficult. Because there wasn't an option for complete beginners to study the subject, the level we were expected to reach was fairly high.
Spanish, however, was much easier. While they wanted you to progress, they seemed to have it in the back of their heads that you couldn't progress too
much so that the beginners' class could be combined with the advanced classes come second year. I have heard that beginner Spanish is relatively easy to do well in provided you do put the work in and go to all your classes (or at the very least the grammar/spoken ones). I also think because you already have studied one language that Spanish will be a little easier for you over someone who has never studied any language before. Word of warning: the Spanish department would not be the most organised department in the world, and it can be difficult to get a straight answer from them if you have any queries about the subject.
As for the timetable, when I was in first year I think I had between 20 - 23 hours of lectures a week, tutorials and language labs included. My subjects were Spanish, French, English and Creative Writing. It was more than some of my friends who avoided taking languages, but I had a lot more continuous assessment assignments than they had, so it evened out come exam time!
Btw, if you are looking for an 'easy' subject, I would really recommend looking into English. As far as I know they've done away with exams for first years, so your assignments would all by essay based. In theory the courseload is heavy, but in reality you just need to read one or two texts that will answer the essay question and understand essay formatting (go to a couple of tutorials for that) in order to get a good grade.
Sorry this is so long, hope you find some help in my waffle