UK Landlord Forum / Life

I need help writing a description of my property to prepare listing for sale:  I am the freeholder of a detached house with walled garden.  The building has a cellar which I use exclusively, a small ground floor flat which is on a long term lease of 99 years, and a first floor which is larger because it extends with an additional wing.  I am not sure if I describe this property as a Freehold that "includes" a small leasehold flat of which I am the landlord, OR if I should describe it as a Freehold with an attached  leasehold flat.
The confusion is that the owners of the long term lease purchased their lease for £150K ten years ago from the previous leaseholder, and then extended the lease to 99 years by paying me a premium last year.   
So if I sell my Freehold ownership of the building and land it stands on, which includes being the Landlord of the ground floor Leasehold flat, how should I describe the property as a whole?  It's important to me to get this right, as I am selling my family home of 50 years, which is very stressfull.
Thanks in advance for any professional advice, Milaena