You will need to confirm with your Solicitor if there is a specific reason that this may be necessary but in a standard case scenario there should be no need. The land registry map defines the boundary of the site. The permission for the building is covered by your planning permission.
Kind regards,
Eilish
Land Registry (or PRAI as they are now known) will provide maps that contain features as shown on ordnance Survey maps. So if the area you're living in hasnt been updated by the OS then those extensions wont show up on the PRAI maps. As stated above the Land Reg / PRAI maps are used primarily for indentifying your site boundaries and any buildings shown thereon are not important or necessary with regards to title issues.