As per photos i have cracks / uneven pattern - its upstairs on the exterior connecting walls Is this a big issue or just a case of a plasterer fixing this up? Many thanks Ryan
It's caused by your roof moving about. The roof expands and contracts and is nicely connected to the top-most blocks on the wall, so they move as the roof moves and crack one block down. This is a fairly common issue. It's nothing to worry about, but it is a pain. You can repair the cracks, but I am afraid it could well happen again. In theory, it could be fixed by stitching over the cracks with long braces, but this is a messy albeit not difficult process. I say in theory, because it should work, but I have never done it so I can't be completely sure.
Personally I'd get a reputable builder to check it out...just to be sure it's not connected with a 'roof sag' or wall plate issue etc.,