How long should I rest before going for work after a normal cardiac angiogram?

One day. You can go to work the next day, providing that you don't have to do physical work (lifting, etc.) which you can do after 5 days. If you had an angiogram via the radial artery (wrist) you can go back to physical exercise in 3 days.
2 days. Part of the answer depends on the nature of your work. If you had an angiogram without and percutaneous procedure, such as stent placement the average recuperative period is 24-48 hours. While you may ambulate sooner, refrain from lifting heavy objects for several days. For definitive instructions, always consult the physician performing your particular procedure.