The ferry ticket is available at Pak Ba Ra pier as well. You can also book tour package from local several operators on main land or buying it on the island. You can book one way if your plan is flexible and buying return ticket on the island. If your trip is fixed, you can also buy return ticket on the main land.
Please note that there is no pier at Lipe but the way to get to the Lipe Beach is a unique service. The ferry will drop all travelers at the pontoon then take longtail boat to the beach.
There is nothing to worried for manage your trip to Lipe or anywhere in Thailand. Thailand has many tourists over 14 mmillion visitors in every year. We have learned and develop to make comfortable transports. Once you said to hotel reception or tour desk, they will recommend the best way to get to the places.