What would the British government do if the people decide to leave the EU?

If the British people decide to leave the EU, then there will be a lot of questions facing the British government. The British government has to negotiate new trading deals and political and military cooperation deals. Moreover, the British government has to deal with the existing EU workers in Britain. The current government or even the future government prefer the option of staying in the EU and other nations may also want Britain to stay in the EU; therefore, it is possible for the British government to negotiate with the EU and make some deals which have no significant differences from the EU pack.