Can you clarify a couple of things in you diagram?
I have IC4a as a 4025 so is IC4b a 4025 as well? Yes, the usual convention is the designate parts of an IC as a, b, c, etc. In the case of IC4b, connect 2 inputs together to form a 2 input gate. However, see the second suggestion below
Also the componets shown as triangles with the not symbol are these standard inverters eg 4069 ? They are inverters, but they can be unused parts of the NAND and NOR gates as in your digital clock circuit, eg. IC2b (under the Min Tens 7 segment display) You can use the 4069 if you wish, but it won't be necessary if there are enough spare gates
Brett.