intrepid travel cancels all trips to nepal until at least may 11 .
customers with bookings offered full refund or trip somewhere else .
nepal expert at kuoni warns tourists to expect a ` frenzy , ' and that they wo n't be ` a priority '
foreign office 's main focus is ensuring britons keep themselves safe .
helpline set up to offer advice for anyone caught up in the disaster .
warning to tourists heading out to the region to be aware that the area is always ` at high risk ' of earthquakes .
queues begin to build at tribhuvan international airport as tourists look to leave nepal as soon as possible .