Thanks so much for your thoughts and comments! I really appreciate your insights as these will be informed by your experiences. Though checking them out, reading a website only provides pieces of information and often misses the 'heart'.
We don't have a set time planned yet - we'd work our travel dates around what is on. Fred wondered about my definition of 'trad' - I'm particularly drawn to the old English and Scots songs, though don't exclude Irish. Likewise, though some Irish sessions ('mad and furious') are great, they are not what I'm after. Whitehorse, Whitby and Hull sound great, just my cuppa tea in fact. I think the way for us to plan, is to identify the festivals that would be right for us, and bounce around sessions/folk clubs as we travel.