What documents/tests to take are required to get admitted into the UK
college from a foreign country, where the student did not have IB or
A-levels, but just finished regular HS.

You will have to apply via UCAS (www.ucas.com) and they will
personally submit your application and application information to the
universities to which you want to apply. You cannot apply directly to
each University (they only allow this in very rare cases).

There is no "standard" foruma for acceptance because each university
has different standards, so you will simply have to apply and see if
they accept you... I believe you can apply to 6 universities at a
time, if you are rejected from all six, there is a process called
clearing that you may be able to take advantage of.

Please note though, the UCAS service charges a fee.

Unless you are a mature student (officially over 21, but generally
older than that with several years working), you will need
A-levels/AVCE/IB qualifications before universities will consider you.
 For these, apply directly to FE colleges.

The UCAS fee is about £15.  If you apply to only one institution, the
fee is lower - when I applied 2 years ago, the fees were £15 or £5 for
just one institution.  It's generally best to talk to the people in
the department you are applying for first, get an idea of what they
are looking for.