the way i would do this job is pull cables up wall into floor void above or down into floor void below 
then junction box under floor BOTH cables to ring main and route through to the new position from either the ceiling down to socket or up from below depending on route taken for cables, check rcd, and bonding ; )
then junction box under floor BOTH cables to ring main and route through to the new position from either the ceiling down to socket or up from below depending on route taken for cables, check rcd, and bonding ; )
