How do I change the land registry documents to include a house built on land already owned

Hi

Can you let me know how I update land registry for land that is already registered in mine and my husband's names.  We are self builders and the house build is nearing completed and we are expecting a building certificate shortly.  We have registered the address with Royal Mail. 

Can you point me to the right documentation to complete to register our home ?  

With thanks
 

Hi Julie - see this thread for how to apply to update the register
Change the property description in the property register · HM Land Registry