I don't know about scar tissue but second opinion springs to mind as this sounds odd.
Might be worth joining & posting on the 'MidwiferyUK' yahoo group as the MW on there are fab at explaining & offering options.
Guidelines on placentas located close to the cervix can be found on the Royal College of Midwives (RCM) & MIDIRS website, maybe even the RCOG website. I think (& please don't quote me) that if the placenta is further away than 2-4 cms from the cervix, most trust guidelines will offer you a vaginal birth. I know there is a stage/position where they advise a C-sec.
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