It's just a phrase that helps the speaker set themselves. In the past people have said "right" or "okay" or "basically". It is so common , particularly when people are interviews on Radio 4. i think most of us have stock phrases we use
Pah.....do your worst, Mr Canine Banana......I know what happened to Harry the school hamster......!
Bertrum....no.....Quiet was an order and rarely obeyed.....Right or So could be followed by anything......Get your books out....or...... Time for gold stars and treats......always worth a listen..... :-)