In reply to Matt300:
Camping Mer de Glace is great. Covered area and a room to meet, charge 'phones, have a brew. Computers for meteo / OHM forecast and conditions updates. Pizza van visits. Walking distance to Flegere lift, restaurants, small shops, station. 20 min walk to Cham town centre along river. Lots of climbers. Immaculate facilities. Pitches / prices from basic in trees to hedged areas with power.
Disadvantages: Can be busy, mid price for Cham. and close to helicopter rescue centre.