In particular I wanted help with how Mussolini came to power, the significance of the march on rome and also his economic policies and declaration of dictatorship upon the murder of Matteotti, once agin I would be grateful if someone could summarise how these events occurred.
The 'March on Rome' was the culmination in a series of events which led to Mussolini becoming Prime Minister, which can be traced from May 1921 to October 1922. Mussolini's fascists gained 35 seats in the May 1921 election. His task was then to convince the middle classes (especially),conservatives, landowners and industrialists that only Fascism could replace the Liberals and stop the Socialists. This meant changing the public image of the Fascist Party which led to opposition from some of his own part memebers.
Mussolini was helped by divisions within the Liberals, unstable governments and a growing breakdown of law and order (mainly caused by the Fascists). In October 1921 Mussolini established the National Fascist Party which gave him greater control of the movement. He then began to take measures to win over the Roman Catholic Church and conservative Italians by stressing his patriotism and commitment to strong government. At the same time Mussolini continued to use violence to weaken the opposition and show Italy that a strong leader was needed. A Socialist general strike in July 1922 was a failure and helped convince many people that the Fascists would bring law and order.
Many Fascists wanted to take power by a coup d'etat
and Mussolini kept them happy by planning the March on Rome. However, it seems that Mussolini actually intended the March as a means of forcing poloticians to make him Prime Minister, rather than taking power by force. He carefully reassured the King (Victor Emmanuel) that he was not going to overthrow him. This was important because the King controlled the Army.
On October 27th 1922 Fascists took over town halls, telephone exchanges and railway stations across northern Italy. The next day the government took measures to stop the advance of the Fascists, but then the King changed his mind and stopped the preparations. Presumably he hoped that a government including Fascists would strengthen Italy. Mussolini refused to accept any other postion than Prime Minister and got his wish on 29th October 1922. However, he was not in complete control and the Fascist dictatorship did not arrive until 1924.
As a further source of information I would recommend the Access to History book 'Italy: the Rise of Fascism 1915-1945', 3rd edition, by Mark Robson, published in 2006 (the Amazon listing is here
). It's an A-Level textbook, but very thorough. There doesn't seem to be much on Mussolini at GCSE level. The information given is derived from this book.