It's not so much the sloping ground that you should worry about, it's the fact that there is a chance that people will find it, or worse, that the police will find it and perhaps watch the spot to see who comes to tend the plants.
A place much further from home, perhaps underneath power lines or along a railroad bed, would likely be safer.
I don't know what part of Ireland you're in, but unless you are along the SE coast, where it's a bit drier in summer, I'd definitely look for a grow spot that gets early morning sunshine and is exposed to the breeze, or choose a strain bred to be grown outdoors in a wetter climate such as Vancouver Island.