I mean that people travel to the "ordinary" meetups here in Edinburgh from Glasgow, from the coast of Argyll (car to station, change trains in Glasgow) and from some distance north of Aberdeen. We have had lunch meets in Aberdeen, Glasgow and Inverary, not to mention those in St Andrews and Thornton. People came to those from all over Scotland, and indeed have come from the midlands of #England, not just from the north. If people want to meet, they will come.
By a holiday in the area where a "conference" takes place, I don't mean that they travel there just to see strangers. They could travel for a week in a place in the Uk that they have never visited before, and spend part of one day of it putting face to names and the other six and a half sight-seeing.
If travel abroad becomes fraught after Brexit/noBrexit, a holiday in the UK may become cheaper and easier to do that flying to faraway places!