The financial arrangements on divorce are usually settled by agreement.  It is important to get the court to make an order incorporating the terms of the agreement - an 'ancillary relief order by consent'.  

 The purpose is to achieve certainty, because either party to a marriage can make a financial claim against the other at any time after the end of the marriage.  There is no time limit for such a claim, and it is not unheard of for a claim to made many years after the end of a marriage.  The only things that can prevent such a financial claim being made are if the person making the claim has remarried (although even then they may be able to proceed with a claim if it was included in the original divorce petition) or if the court has made an order creating a 'clean break'.