Most home printers are not able to print right to the edge of the page. The space around the edge is required by the printer to grip and control paper flow through the machine. If you own an A3 printer, you can simply print your A4 document on that and trim it down, but this is not the best solution. If not, most professional print shops can print to the edge of the page and will be able to get the job done for a minimal cost.