Do you need a Chinese visa when visiting the country for less than a week if u are holding British passport?

You need the Visa to enter the country, regardless of length of stay. It is an "entry" visa.

If you are from the UK NO you dont need a visa for Hong Kong unless you plan to stay for more than 1 month, It's part of the agreement made during the hand over to the Chinese. If you are not from the UK check with the Chinese Embassy or your foreign affairs office.

You do require a visa to enter Hong Kong as this has now been handed over to the Chinese. Last time I checked the visa cost was about 40 - 50 pounds sterling.

No you don't need a visa to stay in Hong Kong. If memories serves you can stay for quite a while too, not sure if it's 3 or 6 months. Same applies to Macau. You do need a visa to travel to mainland China. This easy to get in HK.

Yes, you do. It doesn't matter how long you are staying.

If you're just talking about Hong Kong, no, you don't need one. You don't need one for Macau either. You only need one for mainland china. Even though these territories are adminstered by the PRC, they have seperate entry requirements. Even people coming from mainland china have to go through immigration upon arrival. Interestingly, with a UK passport you have more access to Hong Kong than the mainland Chinese. They can only stay 7 days without a visa.