The situations when you'll need planning consent for your caravan or mobile home
It is often perfectly possible to get the planning consent that you may need for a caravan, mobile home or lodge, but you may not even need it.
For example, if you are doing a custom-build or a self-build, or a major renovation project that renders your existing house uninhabitable, then you do not need planning consent to temporarily live in a caravan or mobile home on-site. You will, of course, need planning consent for the new build or major renovation itself.
In English law, a 'caravan' is any structure built for human habitation which is capable of being moved from one place to another. So 'touring' caravans (those towed by cars) and mobile homes / static caravans and movable lodges are all legally 'caravans'.
So for all these types of 'caravan', you will need planning consent if:
you want to use it as a primary residence or
you want to hire it out to others as paid-for accommodation (either long-term or as a holiday let) or
you want to use it for other business uses.
Often such planning consent will be entirely possible. You should get advice as to your specific situation.
You will not need planning permission if a 'caravan' is parked in your residential drive or sited in your garden (but not a separate paddock etc) and if it is used by occupants who continue to use the facilities of the main house, provided they are:
members of your household or
close family or
other short term non-paying guests.
This is because it's the change of use of land that triggers the need for planning permission and the above do not count as different to the normal residential use of the existing home, which includes the drive and garden immediately around it.
If you own a caravan that is being used in a way the means you or a previous owner should have obtained planning permission but didn't, it might be wise to apply to get a 'certificate of lawfulness' if it has been continuously used in that way and in that location, for 10 years or more - and if you can prove it.