Thanks for your enquiry.
A conditional Contract is very much binding on both parties, if the condition is met!
Basically, what happens is as follows;-
Once the Buyer has carried out the appropriate searches/ his Solicitor checked the title etc, Contracts will be exchange din the normal fashion, and the Buyer will pay a 10% Deposit.
There will be a clause in the Contract stipulating that completion will take place X days after Planning permission has been obtained/requisite Licence has been obtained, provided that if either of these conditions are not met within say 6 or 12 months then either party is free to cancel the Contract and any Deposit is to be returned to the Buyer.
Therefore, provided planning permission/licence is obtained, then the Buyer is legally bound to complete in accordance with the Contract.
It would be normal for the Buyer to spend the time and money on obtaining planning permission and the Licence. You are of course free to help with obtaining the Licence if so required.
I hope this gives you an overview. Not sure if you want me to go into more detail?
Perhaps you could let me know if you require any further assistance.