Hello and thanks for using Just Answer.
I am Al and am happy to assist you with your enquiry.
Generally- if your property is registered at the Land Registry (ie it was registered when your Seller owned the property), it shouldn't take the Land Registry to register the Transfer, transferring the property to you, 3 months. There is a backlog with Land Registry but these are usually in respect of unregistered proeprties which are being registered for the first time.
Likewise, your Solicitor can ask the Land Registry to "expedite" your application. Most Solicitors have their own dedicated Land Registry team, and in the hope that your Solicitor has such a team, I would hope they would ask that your application be taken priority, bearing in mind the circumstances.
If the worst comes to the worst and your application is not completed by the time your Buyer is ready, it is not ideal, but the respective Solicitors can agree to complete with a condition put in the Contract that your title is to be registered and that the Buyer will be indemnified for any problem encountered with your registration. I must say this would all depend on how lenient your Buyers Solicitor is- some may agree to it, while the majority will insist on delaying completion until your registration has been completed.
The only other alternative, which should satisfy most Buyers Solicitors is that your Solicitor agrees to hold the Sale monies in his client acoc**t until your regstration has been completed. This will allow completion to take place but you would not be entitled to the net proceeds of sale until the registration has been completed. This of course would be no good to you if you have a related purchase.
Sorry I can't give you a magical solution, but hope I have assisted.