Curacao...www,curacao.com
Meets all your requirements, most of the dive sites are also beaches and the few that aren't have dive docks. 90% pf tje sites also have an on site dive operation and food. Multiple boat operations on different parts of the island as some of the best dives are boat only.
I believe there's 47 marked shore dive sites mostly along the west side of the island. IMO it's better than Bonaire - certainly there's 10x the non-dive diversions.
Also below the hurricane belt which is a consideration in October,
IMO the best diving is west but it's also pretty quiet. We later moved back to the Piscadera Bay resort area to be near both diving and dining/nightlife plus downtown..
Lions Dive Resort a few minutes east of town is near most things. There's even a dolphin dive there with Ocean Encounters if that's of interest.
The farthest town west is Westpunt which is near some of the best dives but it's pretty quiet - about a 45min. drive back to town. Not even a lot of dining options. Lodge Kura Hulanda is as nice as it looks..
What you won't see there is a lot of big stuff. We saw maybe 1-2 sharks in 10 days of 3-4 dives/day. Some stingrays, lots of small creatures like seahorses and frogfish and a lot of eels. The reefs are in nice shape overall - many once you leave town are a short surface swim out to the minor drop-off. My buddy is a photographer and he found plenty of interest. The city itself is fun, it;s bisected by the port so there's a swinging pedestrian bridge plus the old downtown with all the brightly colored buildings you see on their ads/website.
I can't speak for coming from London but it's fairly easy for us. Look at KLM flights - most of those are non-stop since it's a former Netherlands Antille..English is widely spoken there also although all the signs etc. are metric and Dutch.
Bonaire is also 50 miles away if you want to split your time - it;s the shore diving capital of the Caribbean, More dive istes, mostly more difficult entries and much less to do there post-dive. IMO it's almost identical diving on both islands.
www.infobonaire.com is one portal.
If you do plan to fly over know that Insel Airlines is having financial difficulties for at least the 3rd time in 5 years or so so may not be reliable. Divi Air is an option if you don;t mind small planes. No interisland boat service exists.
