Hate to be "that guy" but I hope you're getting permission to cut the branches and not just whipping off whatever looks good, as its totally illegal and kinda disrespectful... I know it sounds boring as hell and patronising but please ask first! Forestry Commission usually says yes if you approach them properly, and any private land owners tend to get quite excited by the idea of their wood being used for traditional uses such as bow making. Not cool to steal the stuff though, and gives us as bow makers a bad name
If you do have permission, go nuts! And post pics!
(Is Irish yew still taxus baccata? Or is it actually a slightly varied species, a bit like torreya yew, or even taxus brevifolia?)