Many thanks for a very comprehensive answer Chris and everyone else, certainly helping me get a better general understanding of this concept. I'd say, given the conditions, de-ice prior to the early morning departure is almost a certainty.
My only other question is one of personal interest. I believe I'm right in thinking that tanking can be done on multiple sectors, however I got completely shunned by a fellow student who said its an economic no no to complete tanking on multi-sectors, however I disagree.
Anyone's views would be great