Chalet Croix Blanche can easily be reached by car, train or plane. The final road up the mountain from Sion (Route d'Hérens) is maintained and so is generally accessible without snow chains (though snow chains are compulsory in winter). The road goes through some lovely and typical Swiss mountain villages, the largest of which is Vex (pronounced Vey). Driving directions from Geneva can be found here
The closest major airport is Geneva and is 174 km away (around 2 hours) from the chalet. The usual scheduled airlines fly there, including BA, Swiss, Lufthansa, KLM, Air France, etc..., from most of the major European cities. The economy airlines such as EasyJet, BMI and Flybe also offer a service to Geneva. You can also fly to Zurich or into Milan.
You can then either hire a car at the airport (it is best to pre-book) or take the train to Sion (or Visp, which is 45km further up the valley from Sion). In Winter all cars hired in Switzerland will be equipped with Winter tyres which means that snow chains will rarely need to be deployed. There are 2 fast trains per hour and the train station is just 300m from the Geneva arrival level. Tickets can be purchased there and then (www.sbb.ch/en/home.html). There is also a wide range of Limo and Shuttle Van transit services.
www.toandfromtheairport.com/geneva.html offers advice and links to train and road transit services.
The closest airport is Sion, which is literally at the bottom of the mountain from the chalet and is only 17 km away (20 minutes drive). There are taxis available at Sion Airport and it is not worth pre-booking a transit service as the drive up the mountain is so short.
To travel by train you can take the Eurostar to Paris, Gare du Nord and then connect to trains to Sion www.raileurope.co.uk/sncf.aspx
Sion is on the main line between Geneva/Lausanne and Milan and most trains stop there. Each hour there are several express and local trains in both directions. See https://www.sbb.ch/en/timetable.html for timetable and connections. There are taxis available at Sion Airport and it is not worth pre-booking a transit service as the drive up the mountain is so short.
Calais to Chalet Croix Blanche is around 900 km (and takes around 9-10 hours) via the Autoroute. You can plan your route on Google Maps by entering your current location into here.
From Calais, take the Autoroute to Reims, then Troyes then Dijon and onto Besançon. From Besançon, the route goes through a number of towns and villages, crossing the Swiss border a little after the town of Jougne.
Motorways in Switzerland have an obligatory road tax called the 'Vignette' which costs 40CHF for a year. This can purchased at all border crossings. Winter tyres or chains are also compulsory in Switzerland in winter.
The route goes on within Switzerland and skirts round Lausanne which is at the northern shores of Lake Geneva and then continues eastwards following the main road round Lake Geneva. At the eastern tip of the lake, the road continues south to Martigny and then to the east to Sion. At Sion, the route up the mountain goes through Vex and Hérémence. Chalet Croix Blanche is easily found on the Chemin du Tennis a few hundred meters down from the centre of Les Masses.
If you are breaking your journey, Besançon is as good a place as any as it is the last major town in France and has a tremendous cultural and historical heritage. It is reputed to have one of the most beautiful historic centres of any major town in France. Alternatives would be Vevey and Montreux - both of which have stunning views of Lake Geneva.
A downloadable document which provides detailed driving directions from Geneva airport can be found here. It sounds more complicated than it is. Essentially, out of Geneva follow signs to Lausanne. Once you are approaching Lausanne follow signs to Simplon and once you get to Sion (well before Simplon!), go up the Val d’Herens following signs for Les Collons, and then Les Masses. In Les Masses, start to go down the mountain leaving the shops and the Agency ALM to your left and you will see the Tennis courts - Chalet Croix Blanche is literally opposite them on the road beneath them.
Les Masses is part of the Thyon-Printze region and is at the eastern end of the Four Valleys.
The closest ski lift (Les Masses) is a short walk from the chalet. The chalet is a few hundred metres from the Les Masses ski lift which has recently been upgraded to a four man chair on top of a 200 place car park. There is a lift inside the car park which shortens the walk to the ski lift. The hamlet of Les Masses is easily within walking distance and the larger towns of Les Collons and Thyon are both a short drive away.