Will 24 hour free cover leaving Shuangliu airport for a hotel?

Hi,
I am travelling from England to Thailand with an 8 hour layover in Chengdu.
We are going to leave the airport and sleep in a hotel nearby for 6 hours.
Will we need to do anything in advance so that we can do this? Will a 24 hour transit pass be enough or will we need a visa?

Thanks,

Harriet