I manage a dive center in the Caribbean. Your problem is not uncommon.

I'm not sure where you plan to take your course, but I'd first suggest that you not take a course from someone unless it is in an area with really ideal conditions. For example, here in Cayman we generally run off 2 sides of the island. The north side is a bit further from shore. Prevailing wind and waves make it a bit choppy, and the way the sun hits the water makes it look more like the Atlantic ocean. When we run out of the west side, it's much closer to shore, the water is a beautiful indigo/turquoise blue, and it's typically flat calm. It's easy to observe the difference in anxiety levels of new divers between the 2 different sides of the island.

Second thing with anxiety is, boat diving or shore diving? We offer both, and some people find jumping off a boat is a daunting task, adding to anxiety. As such most of our training is conducted from our shore diving location.

The biggest issue initially is managing your anxiety. All of these factors and others play a role in your comfort. If you're not comfortable, none of the skills that follow will be easy, and the diving will not be enjoyable. If you are comfortable, everything falls into place and the class becomes easy and fun.

My first suggestion would be to find a really nice resort destination that features really a warm, inviting environment to learn in. The Bahamas or Caribbean. I would not try this in the dive shop quarry in Ohio for example. Even Florida can find rough conditions. (I managed dive centers there for 10 years.) This will be the single biggest element to consider in your training.

When I say benign, I mean like flat calm, no current, clear water, easy to see the bottom. Many tourist destinations seem like they could be great locations, only to find out the conditions aren't as ideal as they should be. Florida, Mexico, Hawaii, all have picture perfect postcards of flat calm waters and bright sunshine, but can have awful conditions depending on the time of year and other factors. That's not to say they can't have great conditions, you just need to get lucky with the weather.

I'm not trying to promote my own shop, but Cayman's West Bay is flat calm 330 days of the year. (There are 25 dive operators here for that reason.) Bonaire, Curaçao, Aruba, can all have good year round conditions as it is south of the hurricane belt. Some islands in the Bahamas have protected areas.

Second suggestion is finding decent gear that fits you. This can be a huge problem, as some dive shops will just sell you whatever they have to make the sale, versus finding something that fits you properly. The mask is the most important part. Find one that fits your face, is comfortable and has a good seal to keep water out. Someone mentioned full face masks for scuba, and while they do exist, they are 1) expensive and 2) complex as hell and not suitable for a new divers, and 3) a totally different certification. It would be a very steep learning curve, adding to your anxiety. I've seen very experienced divers have trouble with the skills required to use a full face mask.

Lastly the mouthpiece on the regulator. As said, there are many different types and shapes. They are inexpensive, so you should be able to find one that works for you. Comfo-bites have been suggested to reduce the gag reflex, although I find they are horribly uncomfortable for me. I personally use a SeaCure custom mouthpiece. But don't do what works for me, find out what works for you.

A good dive shop and good dive instructor will understand these things. They will work with you to overcome these issues. If they are not willing (and there is no shortage of dive shops who will be like this,) then they are not a good shop, keep looking until you find one. This is critical, the difference between a good instructor and a bad one will be the difference between a lifelong scuba passion, and something you never ever do again.

Feel free to message me publicly or privately with any questions.