Try expanding the image up to the necessary size, and then print it on your normal printer.
Many printer drivers these days have the facility to "poster print" on A4 paper - even the humblest of inkjets.
Sometimes the facility is called "multiple page"
You'll probably need to go into the printer preferences to select it.
Both my HP and Brother printers support the feature - the Brother can do 5x5 pages, the HP goes up to 4x4.