Ocen Water Temps. during October will tend to run in a range from the mid-to-high-70º (warmer early in the moth, cooling later) and general just fine for extended periods swimming and watersports.
BERMUDA CLIMATE DATE--
There is an excellent inventory of fine 'self-catering', private rental properties available in Bermuda. You should check out these first-rate, entirely reputable and reliable agencies for selection, rates and availability...predicated on your own personal preferences, priorities, special needs and BUDGET--
You might also check out the listings of--
with some additional inventory but a lot of duplicatations of those also offered through Bermuda Rentals.
Given your preference for, "..near/on a beach.." you should probably be looking for alternatives in the '..CENTRAL.' portion of Bermuda, in Warwick, Southampton parishes and some of the near '..WEST..' properties in Sandys Parish.
You should also orient and familiarize yourself with Bermuda's layout and relative locations--
BERMUDA--Handy Reference Map--(Orientation, layout, relative locations)
There wil be supmarkets and mini-mart/convenience stores conveniently located along the regular travel and public transportation routes to/from almost everywhere in Bermuda.
With the possible exception of Horseshoe Bay when there are cruise ships berthed in Bermuda, spectacularly beautiful, UN-crowded beaches are the '..norm..', rather than the exception in Bermuda.
As for '..disappointment..'...I can't imagine anyone being the least bit '..disappointed..' in Bermuda and all that she has to offer...but there's no accounting for individual preferences and tastes. Bermuda is incredibly beautiful, has magnificent beaches, is safe, friendly, hospitable and genuinely '..comfortable..'. Frankly, Bermuda is the '..gold standard..' upon which these things are compared.