Crimes Against Humanity and War Crimes Act 2000
17. Every person who resists or wilfully obstructs an official of the International Criminal Court in the execution of their duty or any person lawfully acting in aid of such an official
(a) is guilty of an indictable offence and liable to imprisonment for a term of not more than two years; or
(b) is guilty of an offence punishable on summary conviction.
Individual criminal responsibility
National penalties
Corruptly influencing a witness, obstructing or interfering with the attendance or testimony of a witness, retaliating against a witness for giving testimony or destroying, tampering with or interfering with the collection of evidence
Impeding, intimidating or corruptly influencing an official of the Court
EDIT.