if you remarry or start to live with someone else after the consent order has been granted,can your Ex have the order changed.Not from a maintaince point but from sale of house and share each and pension share clean break.
if so how long after is it safe to live with someone
It depends what the order says. If there is a property involved is could be that there is a 'mesher' order where the property is to be sold when a trigger point is reached. Usually this would be death, remarriage, cohabitation for 6 months or the youngest child completing full time education.
However, from your question it sounds as though you are wondering if the order can be set aside due to a decision to form a long-term relationship. If that is the case, it depends very much upon the circumstances of the case.
If the order had just been granted and you immediately decided to cohabit or marry, that may raise questions. However, your state of mind before the marriage had ended and the finances remained unresolved can alter dramatically once it is all behind you. It would be quite difficult for your ex to demonstrate that it was your plan all along to settle down after the order was made - particularly so if you were not in a relationship at the time.
There is no definitive answer but if you met someone after the order was made, it would be impossible to say this was planned. Even if you were in a relationship, if you were truthful that you had no plans to remarry or cohabit, you should have nothing to worry about. The order is not meant to prevent you from moving on with your life and having new relationships (quite the opposite in fact!)