We applied to OSCR and the basically have a set of criteria you must fit- we were animal welfare.
They have a constitution form on-line, that you can just adapt and send of ( we didn't do that, which is why it took us 6 months to get registered) and they will reply with advice on anything that needs adapting. Our biggest worry initially was that the site has to be either leased or bought by the charity- we have leased our land for a pound. It is also very worrying to have other people ( the committee) having a say in what you do, they can stop you from doing anything- so make sure you chose people you trust and who will support you fully.
You must also be very careful to stick to the constitution and submit accounts.
There is no check on what you do, it seems craxy really, but I guess they think most people will be genuine about applying as it is quite a faff to get set up.