Q-Celtic in Gaul? and Celtiberian

Hi, Brittonic and Gaulish are said to be almost the same, with
minor differences. Can the same be said of Celtiberian and early
Irish Goidolic, and if so, does this lend support to the idea that Q-
Celtic speakers reached Ireland from Northwestern Iberia, Brittonic
preceding Goidelic in Ireland?

Also, I find in Ramon L. Jimenez' "Caesar Against the Celts":

"One variation of this theory is that Goidelic-speakers, or some of
them (the "Black Irish"), migrated directly from Spain, where Q
Celtic inscriptions have been found in the north."

Then, regarding Q-Celtic in Gaul, he says:

"Also, several linguists have pointed out that the Sequani in eastern
Gaul were Q Celts, and their close association with the Helvetii and
their sub-tribe, the Tigurini-Caesar's first victims in the Gallic
War-suggests that those tribes were also Q Celts. Although Caesar
directed them to return to their homeland, it is conceivable that
they later continued their migration and reached the Atlantic coast,
as some if the Boii and Tigurini did, and from there sailed to
Ireland. It is also significant that many Irish saints and princes
derive their names from the Tigurini."

Can anyone add to or clarify this?

,Michael