Technically your husband can apply to the Court for a Prohibited Steps Order to prevent you moving the younger children back to London until a Court has decided whether or not the move is in the best interests of the children
Given the short nature of the stay in Yorkshire and the wishes of the children i do not think that this would be anything other than a delaying tactic - you will be able to move and bearing that in mind your husband may be sensible enough NOT to issue Court Action
There is no reason why you should not move back to the former matrimonial home whilst your ex remains in Yorkshire - indeed it is a sensible option.
bearing in mind London prices it is unlikely that your ex will be able to force a sale of the property until your youngest is 18 - at which point you would receive a larger share of the equity to reflect your contribution.
You shoudl try and discuss these issues with your husband using Family mediation
I hope that this is of assistance - please ask if you need further details