Would you please tell the vital reason doing TEFL diploma necessarily?
If you want to teach and esp. English as a core subject, don't go for M.Sc. Rather, do Diploma in TEFL and then spare one more year for M.A TEFL. And if this is not the case, simply do M.SC Sociology and you will be at a better stage. Insha'Allah.

There are certain varsities offering TEFL in weekend classes now a days. So, do search and if you find one near to your reach, it can also prove helpful for you.

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"But screw your courage to the sticking place,
And we'll not fail." _Shakespeare, 'Macbeth')