I live in Ireland too, a lot of the "space rules" you will se on this site are for people who have hot summers and a couple of feet of snow in winter. We don't get much snow at all so our hen houses don't need to be near as big because the hens will spend little or no time in the house except for sleeping and laying.
For a 7' by 15' house you could put about 50 or 60 hens in it but your run is very limiting. 10 square feet of outdoor space is an absolute minimum. At 230 square feet your run could hold about 21 hens. If I were you I would go for a smaller house, maybe 6x6 or 7x7 and make the rest into run space. If you wanted 50 hens you would need a 500 square feet run, 7x70' or equivalent.
ETA I would go for about 20 square feet of outside space minimum personally but most of my hens get about 180 square feet of run space each. My main house has 10 hens in it, the house is 4x4 and the run is 25x75. In Ireland you will know that it might snow for a couple of days a year so the only problem weather wise is rain. With the smaller runs(10sq feet per hen) , hens will have the ground in dirt within a few weeks and it will quickly turn to muck and sludge and it will be like that for 8 months of the year, and it isn't pleasant for you or the hens. That is why I would recommend a very big run (research the Balfour system it works very well here if done right) or a tractor system where you move the house around every day or two to fresh grass. The only good thing about all the rain is that grass grows like mad so it isn't in short supply for most of the year. It is also cheaper to build big runs here because chicken wire (1" or 2") will keep most predators out (except for stoat or mink but if you have them you won't keep them out with fencing, they need to be trapped)