Thank you for your question
My name is Clare
i shall do my best to help you but I need some further information first
is the house held in joint names?
has there been a final financial order within the divorce proceedings?
Was that agreement written down in an Order and sealed by the Court?
When was the Decree Absolute?
If you move out you retain the same rights of return and entry as you have now - he cannot exclude you
You have identified the only real risk of the moving out - that he will drag he feet on the sale.
To avoid this stay in close touch with the Estate Agent.
If it is clear that your ex is sabotaging the sale then you may need to apply for an Order that he vacates the house so that you can have conduct of the sale.
I hope that this is of assistance - please ask if you need further details
My apologies for the delay
No you do not need to give hm notice and he does not have the right to change the locks if he give syou a key.
You have every right to re-enter the property when you wish - breaking in if necessary!