I think a NI or all Ireland forum would be a good idea.
Where as other Welsh, Scottish, Cornish etc etc are not really necessary.
The reason being NI is isolated by a too expensive, long and not too comfortable ferry crossing for rallies etc.
So any NI club or member does need to have a primary focus on activities in NI/Ireland with perhaps longer trips to the rest of the UK or further afield.
Which is why posters from NI tend to draw attention to their location.
I live in the West country and our centre enjoys guests on rallies from Wales, the Midlands and much further afield because they can still be on site within a couple of hours without any major delays/costs - this is not the case for NI caravanners wanting to attend any other region/centres rallies.
I know the ferry trips as I have a brother who lives in NI.
For the NI vanners
At my brothers wedding reception I went to the bar several times asking for a Norwegian before I realised they were asking for a "nor wee gin", I don't know what the barman thought when I was asking for it!