Or Ireland can import electricity from France TODAY as we export on average 10 GW continuously, and most of it is already generated by nuclear :-)
Sure enough France exports up to about 4GW to the UK, and the UK exports up to about 1GW to Ireland. Right now, it being the middle of the night here, France sends us about 2.5GW and we sent Ireland about 500 MW.
Electricity being fungible by nature it doesn't really mean anything to say that's French electricity when it reaches Ireland, it could just as easily be British nuclear, or wind power from a Scottish wind farm, or any number of sources or any mix.
It's also a two-way flow; while UK<>Ireland transmission tends to net out to UK->Ireland, it's fairly variable; to a large extent whichever side currently has too much wind is the donor.
Current government plans don't seem to take this into account. 40GW of wind power doesn't seem like "basically enough" when you're doing 10GW exports.
They did at least ban "rebidding" where you get permission to build a wind farm, but you think the price you agreed to isn't what you'd prefer so you just bid again next time like nothing happened. Some of the projects which low balled are now stuck, either build it as promised and collect a smaller profit than you'd hoped for or fuck off, no second chances
The HVDC line to France will help with this; it will less frequently be very windy in Ireland and the UK _and_ France.
Longer term, though, everywhere is going to need a lot more storage (and possibly smart variable demand; remains to be seen how practical that is at scale.)
But it is in itself fairly non-trivial; HVDC cables that long are difficult.