Complex sentence: It was rumoured that the ride will be restricted to over 15 year olds only, due to the horror-style experience, but Thorpe Park has simply placed a "recommendation" that over 12 year old children enter the ride.
Split into simpler sentences: It was rumoured that the ride will be restricted to people pver 15 years of age due to the horror-style experience. However, Thorpe Park has simply placed a "recommendation" that over 12 year old children enter the ride.