Read the section of this guide about finding acts as made.
Printed consolidations (published in in 1973, 1950, 1935 and 1911) are useful as they show you what legislation was in force and how it worked at a set point in time. This makes it easier to research how legislation worked at any point in time.
For example, if you need to find out how a piece of legislation worked in 1947, you could look up the 1950 consolidation, and any changes made to the legislation prior to 1950 would be listed in the schedule printed at the end of the act. You could then look at the earlier 1935 consolidation, in conjunction with any relevant annual volumes dated between 1936 and 1947 (as mentioned in the 1950 consolidation), to trace these changes. This sounds complicated but is much easier than having to look in every annual volume of legislation since the act was created, in the hope of locating changes!
Historic acts online on ComLaw date from 1973, but these acts include schedules which will help you to trace changes to the act before 1973. You can then consult the relevant printed annual volumes of the acts for details about these changes.
If you want to see how an item of legislation worked at a particular date post-1973, the historical data on ComLaw is the place to look.