Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Shannon to Glasgow Prestwick Airport as you normally would.
Shannon (SNN) is the airport you will fly out of if you book a flight from Shannon to Glasgow Prestwick. You should not have trouble finding flights to Glasgow Prestwick from Shannon; the airport handles an average of 0 outbound flights to Glasgow Prestwick per day. You should also have plenty of airline options to choose from since 0 airlines have flights from the Shannon airport to Glasgow Prestwick. It is only a 2.1 mi journey to Shannon (SNN) from Shannon’s city center.