You can always renew the lease of a leasehold...its costs you money but you always have the right to do this.
You also have the right to buy the freehold part but only if certain requirements are met...
edit: I think my post above seemed to sneak in before the ones after it somehow...strange...
“for sale Leasehold with vacant possession by private treaty” means that the tenure of the property is leasehold (you own the property but not the ground that the property stands on ie. This is leased from the freeholder and there is normally a ground rent and service charge to pay.) and is being sold by a private party.
You don't always have a right of renewal. While many contracts will say that you have a right, or that the landlord must ask you first, theres no right that even if your landlord wants to kick you out, he has to let you renew if he wants to..
I dont know what your 2nd point means, but I cant really see it being 100% accurate. Why should I have a right to buy my house off my landlord when he can get a better price else where? I think freedom of contract would trump this.