UK internship prioritises UK local students, but then still UK local students find it difficult to obtain the internship, not to mention overseas. First priority is UK local students, then EU students, then overseas. By the time overseas students get to choose, the popular departments will be full. The chance of getting an internship for HK students is very likely less than 1/3.
I believe the most important thing for you now is to clarify (or confirm) whether if a medical student who dioes NOT have British passport can get internship (houseman) place or at least have an idea of the chance of getting an internship place e.g. 20% or higher? coz if your son cannot get in internship , he cannot get registered in UK, then it would NOT be possible for him to even apply for the Licentiate exam in HK (coz the applicant has to be a registered doctor abroad).
http://www.info.gov.hk/gia/general/201601/20/P201601200538.htm
The above shows the actual number who passed the licensing examination, but the % was not disclosed.
For those overseas-trained
doctors who wished their specialist status to be recognized in Hong Kong,
they had to be certified by HKAM to have training and qualification
comparable to that required of an HKAM Fellow in the relevant specialty.
Director (Cluster Service), HA ("D(CS), HA") supplemented that with the
arrangements to increase the frequency of the Licensing Examination from
once to twice a year and to allow candidates to further attempt any part of
the Licensing Examination, the passing rate of the Licensing Examination
had increased from about 20% (i.e. about 20 candidates) in the past to 30%
to 40% (i.e. about 60 candidates) in 2014 [???].
from "Legislative Council of the Hong Kong Special Administrative Region Finance Committee Report on the examination of the Estimates of Expenditure 2015-2016"