I think you grossly overestimate the strength of the revolutionary movement in Ireland and I think you are also overestimating the ability of the Germans to deliver arms.Why to invade, when you can deliver weapons to the Irish and Irishmen are going to do the fighting for you. The invasion of UK is not going to be a large scale thing, there is no need, but German troops on Ireland are always a possibility.
The only way Germany would consider an invasion of the UK would be if they had already somehow had a smashing victory over the RN, reducing the fleet disparity to at least 50/50. This is... not impossible, but would require luck for the Germans and intense bungling for the British.
My statements were generalizations and supporting Irish is more probable than any kind of invasion.I think you grossly overestimate the strength of the revolutionary movement in Ireland and I think you are also overestimating the ability of the Germans to deliver arms.
The Easter uprising received little support from the general population. It was only after the British executed the ringleaders that it became a rallying point. if they are actively working with the Germans that's a different matter. It should also be pointed that the Irish Catholics Divisions serving in the Army did not exactly rise up in protest or mutiny after the Easter Uprising. The British control the Irish ports, smuggling a few fishing trawlers worth of small arms but you aren't going to ship arms en masse. Also there are plenty of Loyalists the British would be only too happy to arm them. But this is all based off a two sentence OP that offered zero details of how this came about. There's no POD no details, so there's no way to construct any reasonable scenario.My statements were generalizations and supporting Irish is more probable than any kind of invasion.
I may grossly overestimate the strength of revolutionary movement, but it is enough if the Irish are a problem for the British, every British soldier away from Mesopotamia or another battlefield or as a war casualty is a nice bonus for the Central Powers in the case that British are still in war.
The German ability to deliver arms is a completely separate issue, much depends on the peace agreement with the French. Which French ports will be made available for the Germans, etc.? It is clear that smuggling cannot be compared to the situation of OTL, because the previous traffic, which has passed through neutral countries, may in changed circumstances also pass through France.