Re-combining properties

[andrewbarnes]

The previous owners of my house sold off a small (adjoined) piece of the property to be used as an office by a firm of estate agents. Some time after we bought the main house, the additional piece came onto the market, and I bought it back. The original intention was to develop it as a granny-flat or self-catering holiday rental, but for various reasons this did not happen (although I have permission for the change of use from an office) and it is currently standing empty (not suitable for habitation).

I would now like to undo some of the work which was originally done to make it a separate unit, do some work on it, and incorporate it back into the main house. It strikes me that this will be a lot easier if I can re-combine the titles of the two properties as one. Please can someone tell me what process do I need to go through to achieve this ... do I approach the Land Registry, or ???

Thanks