To visit China then Hong Kong then back to China then depart for UK do I need dual or multiple visa

Hi Roberts! As you know, UK citizens can enter HK for free for a stay not over 180 days, so you don't need the entry permit for HK. For mailand China, if you do not qualify for the 72-hour or 144-hour free transit policy for both trips, you should apply for a double-entry permit. I think the first thing is to make clear whether you have access to the free transit policy.