The CO2 cannisters are a waste of space. They will do about 5psi if your lucky. I did repair for someone stranded on M1 last summer, and after three of them the tyre pressure was 13psi. Best thing is to get a bicycle pump.
I know, but his tyre should have been 46psi and the tyre was totally squished, and the nearest service station on the M1 was 17 miles away. Not sure I would be comfortable riding along the M1 at 40mph with a mostly flat tyre.