Applying to set aside financial order

Hi, Does anyone know how long you have to apply to set aside a financial order after the final hearing?
My final hearing was last Monday. I don't feel happy with the settlement although we agreed it within half an hour of arriving at court. The reason I agreed so quickly to my ex's offer was because his solicitor landed a schedule of costs on my barrister at 10pm the night before the hearing, threatening another £26k of costs against me. I felt pressured by this as I only heard about it when I walked into court that morning. I now know this should have been served at least 24 hours before the hearing in order to give me time to make submissions and consider it.
The main reason I am unhappy with the settlement is that my ex refused to have his business valued and as I didn't have a solicitor I didn't know how to officially apply for that. I have emails from him where he states a potential value of the company between £200k-£400k two years ago when we separated and also states I had a 25% share in it.
In his court documents he lied about how long we had been separated and claimed his business was a non-matrimonial asset when in fact for 7 years I supported him and the business while he worked evenings, weekends, school holidays and I took care of the kids and house and everyting else.
This was going to form part of my evidence at the hearing but I felt so threatened by the potential costs order that I agreed too quickly.
Does anyone think I have a chance of getting the order set aside if I provide all evidence to back this up? And how long do I have to do this please?
Many thanks