This is my uninformed guess as to what the situation is.
If Harry comes to Britain for an official engagement, such as the Jubilee, or to visit Charles, he will be provided with full security even if he arrives without notice.
However, if he comes over to hang out with whatever friends he has left, or to 'visit a charity', he has to provide advance notice and cooperate with RAVEC as regards his travel and accommodation arrangements. Also, the security provided might not be full RPP level. Harry thinks he's too important for this, hence the toys from pram.
To repeat, this is just a guess. But it sounds more plausible than the self pitying nonsense Harry is coming up with.