Bringing waste onto land to store it (in skips) and to sort it can require an Environmental Permit (England and Wales).
See the Environment Agency News about today’s fine for operating a waste transfer station without an Environmental Permit. In this case, the offender also admitted to burning waste in the open.
The Environment Agency is the waste regulator in England and Wales.
Even if it is one’s own waste (and every step is taken to stop fires), there are circumstances (eg when a compactor is being used) when storing waste on land can require formal registration with the Environment Agency as an activity that is exempt from the need for an Environmental Permit. It is important to check with representatives of the applicable local Environment Agency region.