Ex intends to move 150 miles away

Hello, I’m looking for advice on where I stand re my son moving away with his mother. My ex is in a long term relationship, engaged and looking to marry within the next year. She is originally from London, but moved to Shropshire , where we married ed and had children. She now wants to return to London, where she has family, with my son. This move will coincide with my son starting secondary school and apparently the school is outstanding compared to the current local secondary school being ‘good’. Neither of us have family in our current area. I have access to my son every other weekend and in a Wednesday evening from around 730. She says she will do the driving for one of my weekends and will give me extra time during holidays and inset days. I am very unhappy about this and want my son to remain in our existing area, surely the additional travel and missing Wednesday is not in my sons best interest. Do you think I stand a chance preventing the move?