What uk uni is the best for business management?

LSE is for economics

Lancaster uni does business management https://www.lancaster.ac.uk/study/undergraduate/courses/business-management-bsc-hons-n102/ Business/management is a very popular course there and they have a new management building on property https://www.lancaster.ac.uk/news/new-multimillion-pound-facilities-for-lancaster-university-management-school-complete

There are other unis, but know this one is a popular choice for this uni and for international students.

Thank you for your reply!
but I don't think i will apply to lancaster as I want to go to top uni. (ofc i'm not saying its uni is good or bad.)
as i believe that business degree helps the future career in general, i was thinking lse would be a good choice in terms of meeting people as they are professional at social science so they tend to have the similar purpose or goal or something. and i think that would be great thing if i could meet those people at uni. but as you mentioned, lse is more like for eco rather than business, and management is not related to business.
then i was looking for ucl, kcl, etc... but somehow ucl doesnt offer business degree except information business something.

Course is most definitely important than prestige of the uni as you want to do something you enjoy. A website called 'Whatuni' https://www.whatuni.com/ if you type in what course you want, it will bring up the uni's that do it.
Then research the uni and ask around at the uni for business opportunities and internships, as that is important too.

Although lancaster is in the top 20, Edinburgh, Bath, Warwick, Durham, they are all up there
https://www.thecompleteuniversityguide.co.uk/league-tables/rankings/business-and-management-studies