stop being a silly chap. Doing AS politics myself this is a question you need to be able to answer straight away...
First off, short introduction, show your opinion. Give examples. You should know examples or be able to use google to find some.
Then start doing some point evidence explanation stuff... Give an example of a constitutional reform i.e the House of Lords one where Labour reduced the no. of hereditary peers to 92. Why is this good? Think of a counter to this... why does this not go far enough. Is the Lords really legitimate now? No, does this legitimacy mean less scrutiny of the elected Commons, and primarily the government (assuming they have a strong majority utilising whips, i.e Blair and his ~140 seat majority allowing the UK to invade Iraq.)
Basically just think of constitutional reforms that have happened, and evaluate their pros and cons. Good luck. Revision is key, need the examples to be snappy (haven't revised meself yet which is why my response isn't so good)