Where are you staying? If it's anywhere but Biras Creek (Sail Caribbean is onsite there) your best choice is DiveBvi - in fact about your only choice on VG.
Dive BVI >> British Virgin Islands Scuba Diving, It's What we do! They're a fun group and run a very professional, safe operation. True valet diving also, give them your gear at he beginning of the week and you'll get it back clean/dry at the end. Casey(F) and Jeff run it, they're good people. Jeff will probably be your DM/Captain part of the time. But all the crew were the same, helpful and reliable.
I haven't been in July but in late spring it was pretty calm. No problems at all getting on/off the boat and often they dive one of the smaller nearby islands and moor up near it so the mooring is protected. We only did one dive where the water was a little rougher and they warned us it could be. You won't be doing that dive anyway as it's Advanced.
Most of the diving will be well within your capabilities as the majority of dives we did (22) never were much deeper than 60'. Dives you might like - the 2 "Alice" sites, Ginger Steps, Thumb Rock, The Chimney, Painted Walls (they may not go there) The Aquarium just 5mins off Virgin Gorda is surprisingly good also - often done as the shallower second dive. Seal Dog Rock is epic and a beginner dive, right on the edge of the Atlantic so they often see sharks there. There's a school of baitfish that've been hanging on the Carib side at least since our first visit in 2005 - they're still there. You can swim in them and they'll part around you. Sometimes Barracuda or other big fish will join you for lunch. Silver scales everywhere. Don't make quick motions around the cuda though...
The Rhone is the signature wreck there it's on the bottom around 70-75' There's a swim-thru in the front half if you're comfortable doing that but the back 1/2 is IMO more interesting and all viewed externally - the wreck has collapsed on itself so there's no penetration allowed. Lots of interesting things to see, DiveBVI will give you a briefing on the ride over. IDK how they rate it but the back should be well within your abilities. One of our group was on about her 10th dive there.
The Indians are also known to be one of the best snorkel spots in the Caribbean. DiveBVI does a day trip over to Anegada to snorkel also on Fridays. It's some sort of marine reserve so pretty pristine. And shallow. No diving though afaik. Ask DiveBVI to work in lunch at the Willy T also one day.
Welcome to The William Thornton - Floating Bar & Resturant
Other things to do on VG: I'm sure you've read about it but the Baths are absolutely worth it. Huge rocks jutting out of the water, good snorkeling (too shallow to dive). There is one public beach area where the cruisers come over from Tortola occasionally but the rest is pretty relaxing.
Some of the beaches are uninhabited. Some only reachable by boat so find someone to take you to one if interested. The BVI's are very boat oriented so that shouldn't bee too hard to find. My group charted a boat one day and did the bar tour - 7 bars on 7 islands. Pusser's Factory Store/Island is pretty entertaining also.
Most beaches are wide, white sand. Often the reef just offshore so snorkeling is good. If you're staying at Little Dix Bay or Mango Bay you've got a good one just off your beach. There's always turtles at Little Dix - they'd go diving for the bottom when we pulled in there to pick up divers.
Rock Cafe is excellent. Nice environment outside and a small but decent bar inside. Mine Shaft Cafe has a buffet once a week - not the best food but the view is good. And mini-golf at a bar - how can you go wrong? On Friday night most people go to the Leverick Bay Beach BBQ, good food, live band, we met some of the DiveBVI crew there then later went dancing at Chez Bamboo. We rented a villa so I can't help with where to stay. Although we did go to Little Dix once - it's very nice. (and pricey)