High blood glucose is the probable outcome as the remaining basal insulin clears the system. Your best bet is to monitor BG closely and to compensate with frequent fast-acting insulin injections if it becomes necessary until you can get a replacement.
I do not know how urgent this is (malfunctioning insulin pumps will lead to DKA very quickly, but that's pumps...). If you are in any doubt, call NHS direct or an ambulance.
Have you got another pen? Maybe the one you use for your daytime injections? If so, use that. If not, get down to the doctors today and get some syringes or a new pen. You'll probably feel quite ill today as you've missed it. Keep testing your sugars regularly x