How long is a piece of string!!!! A separation agreement implies that both parties have agreed all the terms under which they separate. Terms can be agreed between the two separating people hence the term separation agreement. A legal document is drawn up which should include all terms. If agreement cannot be agreed directly mediation can be tried to reach a settlement but be advised that mediators are neither legal or taxation experts and their advice has to be checked. Previous posters are right issues regarding pensions, children, property, maintenance etc. all has to be taken into account. Any mortgage companies I have talked to would not consider me for a mortgage on my own without having a separtion agreement or divorce in place. Costs vary depending on how long it takes I got a quote before I started the process and was not charged any more than was agreed. Basically it is a lot easier in this country to get married than to separate and divorce!!! Good luck.