Hi bamcauliffe, Sorry for the delayed response. I would suggest you to change it to different UK Keyboard layout and change it back to "US" and "United States-International" to check if the issue reoccurs. 
Hello,  I recently purchased a Dell XPS 15. I have found when I use the keyboard that when I press the " button once, nothing appears on the screen. If I press the " button a second time then "" appears on the screen. Or if I press the " button but keep on typing the " appears after the next key stroke. If I press the " button then space bar, then the " will appear but there will not be a space on the screen and I have to press the space bar a second time.   The is the same with the ' button as well. I am not even sure the best way to search this issue on Google or on Dell Support. There is no problem with the button.  I appreciate any help any one has on this matter. Thanks 
Dell XPS 15 9530 Laptop keyboard single and double quote issues