The best UK guidebook still is Pete Knowles (Slime) "White Water South Alps". Nearly all kayak shops have them.
However many people like the French, "Alp-Dauphine" by Stephane Roux-Lionel Fine and Jerome Guerry the distributors are
www.canotier.com
There has all ready been a lot of snow in the South French Alps. Big water late may early June can close off lots of runs. I would go for second week in June when the top end of melt has dropped a little and nearly all the runs are on. Also if this is your first Alps trip, you will need to be care full if you are just route finding out of a guide book.
I have tried every route possible to the French Alps from the UK. Most people in the Uk will go for Dover-Calais. But it is a long way to Dover from say Exeter when we have other channel ports close by.
Problem it’s a 6 hr crossing by normal ferry from Portsmouth 1 1/2 from Dover. Speed ferry can take 4 hrs from Portsmouth, 1 hr Dover.
But it’s around a 5 hr drive to Dover (from Exeter 2 hr to Portsmouth) on expensive UK fuel. It’s also about 60-70 miles further from Calais to the Alps rather than Caen or La-Havre.
However big advantage at Calais Auto Route all the way to Grenoble. These are fast roads around 10 hrs to Briancon. Friend of mine did it in a Fiat Pinot Farino to the Rab campsite in 71/2 hrs. Disadvantage more fuel more tolls (60 Euros each way), but cheaper ferry crossings.
Portsmouth route takes longer but you spend less on fuel and tolls. But you need better road navigation skills with some N roads to route find on. Big disadvantage ferries are more expensive, no cheap early morning crossings. But the total time difference from Exeter is not huge. It’s around 3 1/2. Big advantage from Portsmouth is you rest on the boat meal and beer, have a sleep and are fresher for the long drive.
Total travelling time Exeter to Briancon via Portsmouth is around 22 hrs. This route saves on fuel and tolls (tolls 30 Euros) but loose out on pricy ferries. Total travelling time Exeter to Briancon via Dover is around 18.5 hrs. This route is more expensive on fuel and tolls (tolls 60 Euros) but cheaper ferries and quicker.
Just get the calculator out. Don’t forget French petrol is not that much cheaper than the UK, but diesel is about 80 p per litre.
Best of luck with your trip.
Stuart.