The following reputable sites link to primary sources.
There are 2 different types of legislation (a) primary legislation which are acts and treaties and these form the main backbone of the law and (b) secondary legislation which are Statutory Instruments/Subsidiary legislations and these look to put the meat on the bones and often form more concrete regulations rules and orders.
Acts/Statutes are only passed after debate in Parliament and they aim to draft the act carefully in order to make sure that the correct intention of Parliament is achieved. This means that the terms and phrases used are very different to natural language and can be quite difficult to interpret. It is however an important skill as you will need to do this to use legislation in essays and arguments.
Cases are a very important source as it is a common law country. This means that judgments made become 'part of the law' under the doctrine of precedent. This precedent has grown over 100s of years in certain legal topics such as contract, tort and equity where very little legislation has been made and so the law are the doctrines that have been enshrined in case law.