If you are doing contract law by yourself for a court case, then you need to start at p1 of any textbook with 'contract' in it and read the whole lot.
The contra proferentem rule is used when there is ambiguity and apparently its use is straightforward.
The big thing is that the parties may not agree there is ambiguity in which case one party will resist the use of the rule.
and finally contract/consumer law is governed a lot by previous cases which take the place of statute - hence there may be consumer law s ( x) subsection (y) but a case instead....
hence the need to read a textbook on this to get a feel of the subject
anyway
http://www.e-lawresources.co.uk/Unfair-terms---regulation-by-common-law.php
gives quite a nice overall view and the blue bits are clickable and give the cases the statements are based on