We're off to Europe Friday 31st

Kay and Ian are an Australian couple, retired, who plan to bike ride from Budapest to Amsterdam then splash out on a river boat cruise back to the start. Maybe 1400km, maybe more if we take side trips, maybe less if we are tired or sick or lazy or it’s rainy and we catch a train/boat one day. We plan to stay in a variety of accommodation – time share resorts, house swaps, warm showers, couch surfing, hospitality club and hotels if none of the above are available. We have 3 months, a modest budget and strong legs. Our bikes are packed ready for the long flight.
How hard can it be???