Premises in shop use (Class A1) are able to change to café use (Class A3) providing that the premises is less than 150m2 and subject to the Prior Approval from the Local Planning Authority.
For other material changes of use, such as to a public house (Class A4) or takeaway (Class A5) planning permission will be required because the proposed use would be in a different use class to the existing use and there is no exception made within planning legislation to allow a change of use in this instance (although, in some cases, the reverse is allowed whereby an A3 or an A5 use is permitted to change to an A1 use).
If you do need planning permission, then you will need to consider whether your proposal complies with the Council’s planning policies. These will consider the impact of your proposal in terms of the impact on the vitality and the viability of the shopping area, the impact on neighbours, and the parking and highway implications.
Permission will also be required for commercial extractor flues if cooking is intended to be carried out on the premises.
The placing of tables and chairs on the highway* is very likely to require a licence from the highway authority to allow them to assess factors such as pedestrian movements, sight lines and road safety.
Changes in signage are likely to require express Advertisement Consent.
You may also require the consent of the landlord or landowner for any works.
*Highway refers to footways and verges associated with publicly maintained roads.
The building regulations may apply to certain changes of use of an existing building even though you may think that the work involved in the project will not amount to 'Building Work'. You may wish to contact your local Building Control body for further advice.