Dude. Don't worry about it. This is like golf. You can't rush it. I am just getting into the north atlantic thing too. I have been diving for twenty years, but that was in the pacific and Carribean where the water was clear and warm. I have been talking to some really experienced NE divers and I will tell you the first thing you need to get is a dry suit and take the dry suit class. You can rent everything else until you can buy it, but go in this order. Dry suit, Wing type BCD with back plate for twins, multigas computer. I got this from RJ Hartman at Treasure Cove in Westfield, and he has been on the Doria. Take the Trimix class after you take the drysuit class. When you buy regs (rent them til you can buy your own) get high performance regs you can use for mixed gas. You will want to work toward being able to dive mixed gas and O2 and do decompression dives. It is a different world up here and one I am just begining to enter so I am really in the same place you are. It all seems overwhelming because of the amount of gear needed and the training to go with it. But just think of it like this. You want to dive anyway and you can only do it at your comfort and training level, so a training dive is a fun way to dive too. One problem we have is we are in the dead of winter so the quarry and other places to dive are closed. Work on getting your dry suit and start looking at the history of the wrecks and also at ship plans to get an idea of how ships and boats are layed out. There is more research required in this type of diving than in reef diving, but if you love the water and history it is awesome, and a good way to fill time on cold days in the winter.
Allen