Travelling from the UK on a Nigerian passport

Hi,
i own a Nigerian passport but i have right to remain visa for the united kingdom, so i live and work in the united kingdom.
Myself and a group of friends are travelling to South Korea in July and we will have a transit stop in China for 3 hours.
so we are travelling from London - Beijing - Seoul.
Can you advise if i can use the 24 hours direct transit, if not what is the best visa to apply for?

Thank you