Coming from East, South or West - take the A84 to Villedieu:
The best nearby towm to enter into SatNav is Gavray, about 2km away.
Sortie 37 off A84 at Villedieu
Follow signs around several roundabouts to GAVRAY. You should be on the D9. Follow the D9 for about 15km to Gavray.
(alternative route to Gavray: follow signs to Le Mesnil Garnier - D33 - then on to Gavray, turn left when you meet the D9)
Turn right into town over the river (D7, direction Coutance)
After about 100m, take the next major turn right (D38, direction St Denis le Gast)
You are now going north on the D38 which goes gradually up hill. After about 2km look on the left for a white post with a conical top and a red reflector, and a tiny white sign that says "La Rayrie". [ If you see a driveway on the left with big iron gates then you've gone 100m too far. The turnoff to La Baleine on the right is about 200m too far.]
Follow the tiny road into the Commune de la Rayrie and at the end turn right down the hill towards the house.
SATNAV instructions: Longitude N48:55.471’ Latitude W1:20.178’ (Google maps decimal: 48.9252, -1.3365)
BUT some SATNAVs (eg TomTom) don't have the end of our little road and so won't take you there. The closest navigable point (about 100m south of our place) is Long N48:55.470' Lat W1:20.178 (decimal 48.9245, -1.3363). Once there, just go down the hill.
Another thing: DO NOT LEAVE the A84 at Sortie 38 as TomTom will insist: if you do you'll get lost FOR SURE. TomTom doesn't know that Sortie 37 has been remodelled recenty. Get off at Sortie 37 and take the first right turn at the first roundabout going north-west towards le Mesnil Garnier. TomTom will get grumpy and will keep saying to turn right but ignore it and go straight on. TomTom will go all quiet and sulky, but after a few km will see sense and will take you through Gavray.
London St Pancras - Paris Gare du Nord (Eurostar) approx 2h15mins (from £98 return)
Gare du Nord - Montparnasse Bienvenue (Metro ligne M4) approx 50mins (€1.60)
Montparnasse 3 Vaugirard - Villedieu les Poêle approx 2h50mins (approx €74 return)
It's about 15 minutes by car to La Rayrie, taxi around €30
n.b. at Montparnasse Bienvenue it's a long walk (15 mins underground) from the Metro station to Montparnasse Grande Ligne then Vaugirard is another 5 mins walk to the other end of the station. An alternative route is RER-B to Denfert-Rochereau then take Ligne 6 (Direction Étoile) and get off at Pasteur - a 7-minute walk up tree-lined Boulevard Pasteur. Don't miss the pretty view of the Eiffel Tower behind you as you walk up the hill. Gare Vaugirard is on the right hand side of Bvd Pasteur, past Boulevard de Vaugirard, in amongst a bunch of modern office buildings.
A typical journey from Cambridge is:
Outward: 9-hour [fast 8-hour - late arrival, no fall-back options]
Cambridge - KGX 09h20 - 10h13 [13h45 - 14h30]
London StP - Paris Gare du Nord 11h32 - 14h47 [15h29 - 18h56]
Paris Mont 3 Vaugirard - Villedieu 16h29 - 19h19 [19h59 - 22h48]
Villedieu - Paris Mont 3 Vaugirard 09h25 - 12h15
Paris Gare du Nord - London StP 14h13 - 15h29
KGX - Cambridge 15h52 - 16h54
An alternative route is Gare St Lazare to Lison or Carentan. It's a simpler interchange in Paris but the train journey time is not much shorter than Vaugirard to Villedieu. Also, Lison and Carentan (north of Coutance & St Lo) are each a 1-hour drive from La Rayrie.
If you miss the last train from Gare Vaugirard there is a very comfy Novotel literally next door to the platform, but it's not cheap (€130 - €210) 17, rue du Cotentin tel . 01 53 91 23 75. A cheaper option is on the way up from Pasteur station, the little two-star Hotel Atlantique (€65 - €79) 54, rue Falguière tel. 01 43 20 70 70.
There is a nice Café-Restaurant nearby called Blue Buoî at 50 Bvd de Vaugirard. It has comfy chairs so if you're early for your train then it's a nice place to stop for a café or a beer, or even a meal.