Moving to: Jersey (near France)

I mentioned helmets because when I was there, where I went there were very few pavements, so if you come off unlike the mainland where you hit the pavement and get scrapes and shoulder or collarbone  injury (a la Porte), there you will hit a wall. So there will be some side impact to your head.

I think in that scenario, it changes the risk/benefit calculation, so more consideration in that locale is required.

Re jersey;

Forget about helmet advice, that's utter nonsense, we had this discussion when Jersey polis decided to enforce helmets on kids u14 and there was even an article about it in the graun (which burtthebike commented on) https://www.theguardian.com/environment/bike-blog/2014/jul/30/jersey-com...

Someone worked out that best case scenario IF the helmet actually worked as per in the lab and the children being struck or falling hot their heads in the precise fashion in the lab it MIGHT save a handful of children from a bigger headache ...maybe! Yet the issue is still mostly surrounding driver attitude and highway design, yet again pushing the vulnerable to change their behaviour to keep safe yet with no evidence ever that this works in any environ.

Jersey is much better than most of the UK re cycling safety, maximum speeds are 40mph and even then only on selected roads HOWEVER motorcyclists are the bigger problem by far.

Cycling/driving on the opposite side was easy for me, from the first time I did it getting off the ferry almost 28 years to the day. If you're a logical and thoughtful driver/cyclist then you should have no problem whatsoever.  There are some archaic leftovers like 'La priorité à droite' give way to the right, even though at roundabouts you give way to the left at some junctions even little side roads you give way to the right, they're particularly noticeable in villages and on the edge of town in older parts, generally newer developments don't have them, Paris there is a shit load of them.

It's a bit fucked up tbh as the French Highway code barely gives it a nod but it was the way it used to be everywhere (horse and cart era) and it was left in for the oldies but then it should have simply have been phased out, but you know, France and shizzle!

Small towns and country roads, drivers and usually very respectful, pretty much the speed limit through a small town or village is 18mph/30km/hr and there are usually speed cameras to enforce it.

Bigger towns and cities, honestly it can be just as bad as in the UK, don't believe the hype surrounding how good French drivers are, this is utter bullshit, they have a worse record of crashing and killing on the roads than we do. Overall cyclists don't fare any better than here and cycling as a whole has seen a lull for 25 years and more but is in parts increasing but nowhere near what it used to be, not even close. Oh yeah, roads in towns/cities can be absolutely shocking, if you think our roads are bad, try cycling on a road that slopes off to the gutter and is half broken up cobbles half rotting away tarmac, it aint fun so get your position early.

Cyclists in France tend to hug the gutter, roadies, oldies, lesiure cyclists, sorry but no matter where I've cycled I am not deferring my safety to what the locals might do, you can beep your horn as much as you like - rare but does happen same as here funnily enough!

As for Normandy and Brittany, I love cycling there, it's not lumpy so there's a massive plus, it doesn't have much motorway and though there are increases in general motoring traffic since I was last there, there are loads of back roads to choose from. The only pity is that you can't cycle direct to Mont St.Michael anymore, this was one of my favourite rides ever! A blast from the hotel after I'd already arrived on a short day of my tour, not because I wanted to go see the monument but because the wheather was absolutely chuffing bob on, roads as smooth as a babies bum, conicidentally joining up with a local club ride along the main drag for about 10 miles or so just put the cherry on the icing that day  

People in France still love bikes and cycling, last year on my visit to Lens as part of a rememberence tour I was chatting with a village mayor and dignataries outside the community hall about my bike. My French is passable but sometimes countryside french can be difficult to understand especially when they crack on, luckily there was an ex-pat who was helping out for the visitors for the rememberence service at the memorial to translate. 

Hope Jersey is everything you expect and more and enjoy the jollies over to 'La Belle France', don't forget to grab a few bottles of Normandy brandy in your panniers, there's a huge selection of the local stuff and some places will give you a free taster or three 

Bonne chance

cycling in France is much nicer than most of the UK, more space, less vehicles, quiet country lanes

Jersey is very cycle friendly, they have green lanes where you have priority over cars and cars are limited to 15mph (so pretty much car free as they will take a different route)and drivers even give way to you when they don't need to.
You just have to be careful at junctions because there aren't many pavements, so visibility in/at junctions is not what it is on the main land, as you lose that extra metre of viewing.
Probably a good idea to have a helmet, as there is more likelihood of impact with street furniture, walls and branches due to the road layouts (at least that's how it felt to me).

I haven't a clue about Jersey, but yes you will be able to get to the Cotentin peninsular easily, to the little port of Granville,  and the cycling there is excellent.  As are the restaurants......