It would be better to let your solicitor deal with this. I wonder why you are trying to deal with it?
In the attached weblink, the Land Registry explain how deeds of variation are handled by themselves when registering the new lease. I've had a trawl through some of this stuff (on registering a lease) and suspect that either the clauses used in the way your lease was set up is different from the wording that LR now require (standardised wording is required) or the solicitors don't have enough information to confirm your title to the freehold element.
You say it is a house yet you have a share of the freehold. The way this generally works is you own a share in a management company (shell) that actually holds the freehold. Each of the people holding a lease on the whole of the freehold site would hold such a share. If its a house, what other properties with leases make up the total freehold site? I ask this because such arrangements are clearly more common with a group of flats or apartments.
http://www.landregistry.gov.uk/education/pres_ leases_new/amendment/variation_deed/