You could use something like VeraCrypt which has the hidden volume feature, which essentially allows you to hand over a dummy password if required and it's not possible to prove the existence of a second hidden encrypted volume.Hosting your own data isn’t an effective countermeasure for this, RIPA takes care of that as they can compel you to hand over the keys or put you in prison.
You could argue that you don’t don’t have the keys but I doubt it would ever stand up in court for the simple fact that a judge is never going to believe that you can’t access your own data which you created and host.
They will ask themselves why would you be saving it if you can’t access it yourself and likely conclude your version of events isn’t plausible and draws suspicion and the law enforcement agencies accusation that you are not telling the truth will be more credible.
I guess the only thing you could do is move your data to a services which is outside the scope of U.K. law. There is probably plenty to choose from which kind of defeats the purpose of the law.