Home improvements

We are looking to move to the region in the near future and during our research a question keeps cropping up.

As a tradesman who would want to carry out minor improvements and refurbishments I.e possible new bathroom/ kitchen, tiling,etc  there seem to be licenses required for what I would do in the UK as and when,without having to notifying anyone.

Basically what can you do without going to the town hall and paying a fee? and where do the IVA come into it? If you are only buying materials.

Thank you