Form G is to tell the court whether the parties are ready to go on to the next stage in the court case.
It's a form to be completed by both parties to a divorce in a court case started by an application (by either of them) to court, asking the court to decide how the assets of the marriage should be divided between them.
When the application is made to court, the court sets out a timetable for what the parties must do before before the first hearing (which is called the first appointment). The 1st hearing is set abut 3 months from the date the court receives the application.
Within that 3 months, the parties must each by set dates, file their financial statement in Form E, prepare a chronology of key events, a statement of issues, a questionnaire of the other party, and replies to the questionnaire they have received.
The court sends out to each party a Form G with the timetable and notice of the first appointment, to ask each party if they are ready to proceed to a Financial Dipute Resolution (the FDR) at the first hearing, and if not, why not.
The FDR can only go ahead if both parties have all the documents and financial information that the court has set out in the court timetable, or if the parties are prepared to waive their right to that information and those documents.
So - reasons that someone might put on their Form G as not being ready to proceed to FDR could be - not received the other parties' Form E, or not received answers to their questionnaire etc.
At the first appointment, if both parties are ready, the hearing can go ahead as an FDR. If the parties are not ready, then the district judge will give directions eg the respondent's Form E must be filed within 14 days, and will set a date for the FDR to take place eg in 28 days.
At the FDR, if an agreement is not reached, the case will be listed for a fully contested final hearing.