Eating oysters in Normandy

Oysters would be out of season in May if you go by the "any month with an R rule. So they may be harder to find.

Cancale is in Brittany, so if you were staying there, I’d say anywhere on the north or south coast of Brittany, you’ll find oysters and a lot of other shellfish—even in May. The restaurants are extremely careful with what and how they serve—personal experience. Certainly, Bayeux has a seafood restaurant. They are only ten kilometers from Port-en-Bessin-Huppain, a port town where I’ve eaten shellfish.

research vibrio vulnificus. it is more prevalent in warm waters. That is the risk of eating them in the summer. Dont know if that is an issue in the normandy waters.

It is said that it is best to eat oysters during the "ber" months.
That means September, October, November, December. But in fact the season extends until March
However, you can eat them all year round, they will not taste the same outside of these months and they will be more "milky".
So even in May you will have no trouble finding a seaside restaurant offering oysters.

As mentioned by Bets, Cancale is not in Normandy but in Brittany and 2 hours drive from Bayeux which is a long drive if it is only to eat some oysters. That said Cancale is very pretty and the oysters are excellent (I was there last month)
The oyster farmers set up oyster sales stands with tables on the quays, they also sell white wine. They open the oysters for you, uncork the bottle of wine, then all you have to do is sit down on a table to enjoy. And the price is ridiculously low.

But if Cancale is a bit far away, don't worry, Normandy also has its oysters (the Norman ones). Isigny sur mer, Saint Vaas, etc.
Some varieties have a less iodized taste than those from Brittany.

I don't have a restaurant to recommend, but if you are looking for "fresh out of the ocean", just next to bayeux is the producer "La calvadosienne" (oysters from Asnelles-Meuvaines). it has a shop with a tasting area.
It couldn't be more direct from the ocean.

https://calvadosienne.fr/nos-points-de-vente/la-boutique-dasnelles-et-son-espace-degustation/

You can also go there if you have a sudden craving for a dozen oysters at 2 am, there is a vending machine 24/24 7/7!

Many restaurants in Bayeux serve oysters - hopefully, fresh out of the ocean if not waterfront.

In 2019, we had a great meal at the bistro at the Hotel Villa Lara. This is a great place, but we didn't try the oysters.

https://www.levoletquipenche.fr/le-bistro/

One can find oysters everywhere along the Atlantic Coast in Europe, so Brittany is not exclusive in this respect. It's the combination of freshness and the smell of sea air you only can have in the open air restaurants along seafronts and the reason to go to places like Cancale. Wouldn't be worried about freshness in restaurants more inland.

As noted above, the oysters might be a bit "milky" in May, due to their reproductive cycle. "Milky" here being a euphemism.

However, if you want a coastal dining experience in Normandy, one of the spots you might try is La Vielle Digue, which is open seasonally and may be open in May. It's right at a shellfish processing plant on the harbor of Blainville, northwest of Blainville-sur-Mer on the west coast of the Cotentin peninsula west of Bayeux. This is a place where just-harvested shellfish are kept in constantly flowing seawater tanks for a short time to allow them to disgorge themselves of sand and whatnot. In other words, after they leave that plant they'll be shipped to restaurants elsewhere advertising the freshest seafood possible. At Vielle Digue, they walk out the side door to get them. You be the judge.

Another option just a bit south (you have to go around the harbor to get there) is La Cale, which some consider to be one of the best beachfront bars in the world. They are right on the beach with mostly outdoor but some indoor seating, and also are open seasonally, so you'll have to check. Very fresh seafood, especially shellfish, and a bit more casual and occasionally rowdy than the usual staid French restaurant.

The above places are right in the area where oyster beds are cultivated, so you can't get much fresher stuff, but -- as noted above -- fresh seafood, particularly shellfish, is very common and easy to find all over Normandie.

Barfleur and St Vaast le Hougue

How much are oysters in France? I love oysters and typically on the occasions I do get them, it is at least 3 dozen between me and the wife. And could easily go another dozen.

Agree with Sammy to look for places like Blainville having a tradition of cultivating oysters too. Some restaurants can look a bit basic, but can be the best places for surprisingly good experiences. Off the beaten path and likely visited by the French only, except yourself and those accompany you ofcourse. Maybe your hotel in Bayeux has some good suggestions too.

How much are oysters in France?

The price of oysters depends on its size (caliber), its origin, its type (flat or hollow), the rearing method, the oyster farmer (the brand) and the place where you eat or buy it.
A dozen No. 3 oysters from Cancale or Marennes Oléron bought on the spot directly from the producer is less than 10€.
The same dozen in a local restaurant in Cancale or Oléron will cost around 30€.

A dozen of "Gillardeau" (the Rolls of the oysters) can cost up to 4 times more. Note that if you order Gillardeau oysters at the restaurant, know that each oyster shell is laser engraved to prevent counterfeits.