Your cousin's bank statement in the last three months should not be less than 6,000 pounds (I don't know which bank your cousin is, and some banks need to print their own statements and then go to the bank to stamp them). Then you'd better have a domestic account, which means you have money to travel, and then you have to prove your source of funds, such as your payroll.

Proof from your relatives, preferably from the public.

Your cousin's invitation letter is about inviting you to play, preferably in Chinese and English, printed out and signed by your cousin.

Copy of your cousin's passport, visa and police registration.

That's all. My mother asked for these things when she came to see me last year. Now that the policy has become stricter, I don't know what other materials are needed. I suggest you call the visa center to ask.