UK Immigration laws are rather involved so you may want to hire Immigration Solicitors to aide you in the process. The application process is complicated enough that you will need to understand the options available to assure that you apply for the right “visitor” definition that applies to your visit.
For example, if you are visiting for a short term you may apply as a “general visitor”. A child under 18 years will need to apply as a “child visitor”. Sounds simple enough but then there are several other “visitor” options that define the type of visit. Case in point, is you are visiting a family member who lives in the UK you can apply as a “family visitor”. Or perhaps you are entering as a business person or entertainer, in which case you would apply as a “business” or “entertainer” visitor. The purpose of a visit defines the type of application to enter the United Kingdom.
Also, if you are a visitor from China, entering as a part of a group, there is a separate application called an “ADS visitor” which calls for specific requirements for approval of the application that if not satisfied may result in denial of permission to enter the UK.
Perhaps you wish to enter the UK for the purpose of getting married or have a civil partnership union. The rules are that if you plan to marry and then leave within 6 months you can apply as “visitor for marriage or partnership”. But, if you plant to remain in the UK as a resident after the marriage or partnership you cannot enter as a visitor. You will have to apply under different rules.
Immigration Solicitors will be able to guide you through the somewhat confusing number of visitor titles and help satisfy all the requirements for the application to avoid denial of entry in the UK.