Lawrence says YES.
When selling your property, it is likely that the purchasers lenders solicitor will ask you for your Planning permission.
Where Planning permission is not required, you will have to provide proof.
The only way to prove Planning permission is not required is to produce a LAWFUL DEVELOPMENT CERTIFICATE.
If you do not have a Lawful Development Certificate you will have to apply.
It can take up to 8 weeks to obtain a Lawful Development Certificate.
This is likely to hold up the sale of the your property.
Alternatively in some limited situations you may be able to buy an Insurance Indemnity costing £400+