Generally, a straightforward, undefended divorce takes around 4-6 months, once the divorce petition has been submitted to the Court.

If the divorce is not defended then it can be a reasonably smooth process from issue to the pronouncement of decree nisi (a document from the Court that says that it does not see any reason why you cannot divorce). The divorce does not actually become final until the decree absolute has been issued (this document legally ends your marriage), which you can apply for at any time from six weeks after the decree nisi.

However, if your spouse is not co-operative in the divorce process then this could cause delays in you getting divorced.