You house is similar to mine... Victorian end terrace with rectangular doors and rhomboid door frames.
When i started my kitchen renovation bodge, I stupidly built a sink unit with 90 degree corners, and fitted splash backs around three walls with a spirit level, only to find the room doesn't have any 90 degree corners, nor a level floor so the units on one side needed chocking up to bring them anywhere near the level splash backs... just fitted the skirting boards and i now realise why people buy a house, knock it down and build another one... it's got to be easier in the long run.