Congrats on your service dog and props to you for undertaking the challenge and risk of owner training. Training a dog for public access is no easy task and goes well beyond basic obedience.
Every thing the dog knows must be proofed; basically, the dog must be retrained to act and perform the same under a wide variety of circumstances and environments. That means, for example, he needs to know that "sit" means "butt on the ground" not just in your living room but in every room in the house, on any type of floor surface, on grass or pavement or concrete (you get the idea); that he will obey the command just as well if you're 10 yards away with your back turned as he does when you're standing in front of him facing him; that he'll also obey just as well if you're jumping up and down, if there's a pack of kids playing ball directly next to him, if there's a loud train or truck going by, etc. Everything he knows needs to be that rock solid in his mind.
You'll want to make sure you have the recommendation and support of a medical professional regarding your status as disabled and your need for a service dog to be trained to provide you with functionality that you lack because of the nature of your disability.
What tasks will he be trained to do that mitigate your disability? This is important since simply alerting to seizures is not considered a task that qualifies the dog as a service dog even if the person with the disorder is considered disabled.
I'm not sure where you live, but not all states allow Service Dogs in Training (SDiT) the same public access rights as active Service Dogs. If you're in one of those states, you'll need to contact the owners of establishments that don't normally allow access to pets, like grocery stores, and request permission to bring your SDiT. Otherwise, you can still do plenty of public access training in places that do typically allow pets, like pet stores and some hardware stores, etc. A busy pet store is a good place to work on proofing training since there will be plenty of distractions (other dogs, people, kids, treats & toys, maybe even cats or birds or small mammals or reptiles) for him to practice ignoring.
The Service Dog Central forum
and the Service Dog Central main site
both have a wealth of resources and helpful information. The forum especially is full of knowledgeable folks, many of whom are also owner trainers and can offer you advice and guidance and information. The site and forum are owned and operated by a woman with a seizure disorder who has an owner trained seizure alert dog. She's very active on the forum and always willing to answer questions and share information. (Also her dog is named Tardis and she's a Doctor Who fan which makes her extra awesome in my book.)
Good luck to both you and your dog. I hope he's able to help you gain independence and functionality that you currently lack due to your disability.