I would start slow and accumulate things gradually. My favorite non-slip pad is the Ecogold non-slip hunter pad (Smartpak carries it), it’s not cheap but it’s very durable, washes great, and stays in place great.
If you really want to get new boots, I recommend the Ariat tall insulated ones. Personally, I find the insulated field boots fit better than the insulated dress ones for some reason, so I wear those.
I don’t have anything against the Bobby’s bridles, but my favorite bridles are the KL Select Foxwell bridle (VTO sells it) and I recently picked up an Aramas hunt bridle that is made of lovely leather. But you can wait on this, because again, sometimes you can pick something up on sale, and a flat hunt bridle is not essential.
Hunt coats are tricky. If you can delay, often something will crop up that is your size to be had at a bargain. Otherwise, don’t skimp, because hunt jackets last forever, and you don’t want to be stuck with something uncomfortable or unflattering for the rest of your life. Re: stretch, none of my hunt coats have any stretch. They are wool, and they are tailored to allow for layers underneath and also for movement of the arms, even if you are a gal with the shoulders and arms of someone who stacks too much hay (like me) you should be fine. Definitely don’t buy something that feels restrictive! My fave jackets are from Horse Country in VA, but Shires makes a really warm and nice hunt coat also.
FWIW, I’ve been back into hunting for 3-4 years after a many year lapse and I still usually hunt in a black Samshield (not velvet)–which is the helmet that fits me the best. I’m in the market for the “right” velvet helmet, but I refuse to sacrifice fit/comfort.
I’d put a high priority on getting the right wool socks that fit just right inside your boots, and also on getting the right long underwear/ warm winter breeches. You don’t say where you are located, but if it’s cold, having the right layering system is critical. Also, warm gloves and silk glove liners = essential.