You can change your mind and have the divorce dismissed or even decide to put your divorce on hold at any point up until when the decree absolute is made.
Once the respondent has been served with the petition for the divorce (this can be done by process servers if they refuse) then the decree nisi can be applied for. If the grounds of the petition are accepted the decree nisi will then be pronounced in court. The court will then make an order in relation to finances and once this is agreed the decree absolute will be applied for. It is when the decree absolute is finalised that the marriage is over. The decree absolute has to be applied for at least 6 weeks and 1 day after the decree nisi is pronounced but this can take much longer if there is a complex financial settlement, for example if you are a high net worth individual with pension funds and investments spread out across the world.
If you are unsure about whether you wish to go ahead with your divorce in any stage of the proceedings then it is important you speak to your solicitor to get legal advice as soon as possible.