Where do you start?
It is possible for either party to apply for financial orders, it does not need to be the applicant for the divorce/dissolution proceedings, so you can apply as soon as the proceedings are commenced.
The first thing to look at are the financial assets of your partnership. The Money Advice Service website has an online calculator which will, amongst other things, help you create scenarios for splitting what you have. Next, as this is a fairly complex are of law, it would be very wise to talk to a solicitor to get some basic advice – with Routh Clarke this initial chat is free. If your joint financial situation is fairly limited, there will be little debate on how it should be split and you may be able to agree a way forward with your partner, perhaps through mediation if communication is difficult. If you can agree terms, this can be made legally binding with a consent order.