Planning consent in Chelsea is generally not required if your garage conversion can be called permitted development (pd). If your property was built recently there could be restrictive covenants within the deeds that require your garage to be used only as a parking area, it is possible to discharge this covenant however. In Chelsea you would also require formal approval to alter the use of a detached garage.
Our competent construction team may need to assist you in asking for approval from householder planning if by any chance your pd rights have been revoked. The overall charge would be £500 and you would have to pay the design fees on top of that. If you want to drastically alter the exterior appearance, such as making major changes to the windows, using new materials, or incorporating an extension, a complete application would also be required Listed building consents (if you reside in a listed house) and party wall agreements with any adjacent neighbours are among the other permits you may need to obtain.