In reply to PGD:
We use Snowcard
http://www.snowcard.co.uk/
We were successfully and without any hassle repatriated back to the UK last year when one of our boys broke his collarbone (ironically not whilst climbing, VFing or biking but when playing "what time is it Mr Wolf" at the campsite!!)
I particularly like the fact that you can remove some of the unwanted cover like"tech pack" as we don't take electronic stuff with us other than a cheap mobile. This helps reduce the premium. We looked at BMC but their "family" cover only includes two children! (we have three)
Also possibly Dogtag but not used them
http://www.dogtag.co.uk/
Hope this helps.