If you are serious about learning the organ, you must of course arrange for regular access to an instrument. However, there is a great deal you can do in your own home.
Nowadays digital pipe organs have become very satisfactory for home practice. Many are equipped with key mechanisms that somewhat mimic the tracker action of a proper organ. If you are in Europe, Johannus is one manufacturer you may add to the list given in Doktor Mayhem's answer.
I will assume you are mostly working on your own and offer a few comments that may help someone with your background to avoid traps.
Access to a teacher with a strong performing standard is highly desirable to give you a solid foundation. Organ technique is significantly different from piano technique, and I have found that self-taught players with a piano background underestimate these differences.
While it does take some time to acquire good pedal technique, the true obstacle, typically taking much longer to overcome, is coordination. The left hand and the pedals are felt to be 'bound together' and tend to follow each other, so that contrary motion between them often results in mistakes. If you find it takes you months or even years to overcome this, your experience is normal.
In my opinion, the best way to tackle this challenge is with the Bach sonatas. These beautiful works will stay with you throughout your organ career. They are not for beginners, and are so exacting that many performers avoid them. Despite this, they sound like child's play. Do not expect to master them any time soon, but it's never too early to carefully begin. The Bach sonatas directly attack the fundamental problem of organ playing.
Even so, the most insidious technical challenge in playing the organ is balance. With one hand on one manual, and the other on another higher manual, we tend to turn our shoulders. With both feet engaged in the same extremity of the pedalboard, we tend to turn at the waist. We can easily find ourselves in dangerous twisted positions. If we persist, serious long-term injury can result. The organ is not as difficult as the piano in terms of manual dexterity, but is much more difficult in terms of posture and balance.