If you are an overseas student then if you want to come to the UK to learn to study law (or any other subject) then you are going to need to have a UK visa to allow you to enter into the country.
There are a few different ways you can go about getting a visa. The first way is to actually apply for a student visa uk. This allows you to then come to the UK and study your law course. Applying for a student visa can be quite complex so it is vital that you seek professional legal help. You also need to make sure that the college you are applying to has been approved by the UKBA for the purposes of teaching foreign students.
The next way maybe to enter the UK is by obtaining a spouse visa uk. You can only get a spuse visa if you are married to somebody who already has the right to live in the UK under a visa.
Finally the next obvious way to stay in the UK is to get a UK passport. Applying for british citizenship can be bery complicated and it is always best to seek legal advice. Should you get one thing wrong on your application then it could be refused and your application will be rejected.