Cecilia entry to Oxbridge and the top universities is not really related to what school you go to but to the quality of your application, predicted grades, your personal statement etc., then for Oxbridge there is an interview. Every year at even the most prestigious schools such as Westminster there will be applicants who the school thought were good candidates and had a chance of a place who did not get in and others that did not seem such good applicants who do. It is not that hard work and the right school will get you a place at top universities. You have to have the personal qualities, intellectual curiosity, natural aptitude, evidence that you have a real enthusiasm for your subject, have read widely, can critically appraise what you have read and understand and have your own opinions on the issues raised. All these are qualities any school teaching A level should be aiming to cultivate in you, which is why many many schools send pupils to Oxbridge but often not many pupils. The most prestigious schools, as you have found out, are very selective and just happen to select more pupils who have the potential to get to Oxbridge (but still not all will). The Economics course at LSE is by the way one of the most selective in the world, far more applicants and more selective than most if not all Oxbridge courses.
There are a lot of good UK universities offering excellent courses that will be full of bright pupils, many of whom may have applied but not got into Oxbridge LSE etc. the Complete University Guide provides rankings (I would link but I am in rural England for the weekend and with the slowest of connections) the Russell Group is not actually a marker of quality, it is an alliance but they are all universities that tend to be higher in these tables. You may not have particularly heard of universities such as York, Southampton, Leeds, Bath, Birmingham as much as the ones in Chinese parents minds like Oxbridge, Imperial, LSE, Edinburgh but all may actually be better for some subjects. Got a connection, this is the Economics table [http://www.thecompleteuniversityguide.co.uk/league-tables/rankings?s=Economics] but all those courses in the top 5 are incredibly selective, and will have candidates with predicted 5A*s including Maths and Further Maths not being offered places.
Most importantly I have been doing the rounds of UK universities with my daughters and all those near the top of the rankings have very large contingents of Chinese students and food shops catering for them nearby (something that is important to my daughters 
)
US unis have a similar application process looking for evidence of ability, critical thinking skills etc via SATs, and varying requirements to submit sample essays etc. It is quite time consuming in terms of understanding and meeting all the requirements and helps if the school has experience.
So actually as long as the schools you are considering are able to get the occasional bright pupils A*s and into Oxbrige it does not matter how many. Few getting in may just reflect that it is not a selective school and bright applicants tend to go to other more selective schools.
Go on where you feel most comfortable and will support you to do well, beware of schools making assumptions about you just because you are Chinese, you want a school that will treat you as an individual. I have been Guardian to Chinese friend's daughters in the past (sorry I am past that stage now) and it is very important that it is a school that understands your culture but doesn't expect you to conform to their own stereotypes, beware for instance any school that allows any overseas pupils to stick together and isn't proactive in facilitating and encouraging integration.
Hurt wood House definitely market themselves in the UK as for those wanting to pursue training in the performing arts.