I have wide feet and cannot wear most shoes/boots. I find Birkenstock good for shoes and sandals(they do width fittings), and for walking/trekking shoes I have had good results with Brasher boots/shoes. I buy them in Padmore and Barnes in Kilkenny but many good shops will stock them, including probably Dublin stores referred to earlier.
You can also buy them online, which is not as daft as it sounds. You send a tracing of the outline of your foot wearing the walking socks of your choice. They work out your size and length and send the boots for you to wear indoors. If you're not happy they'll take them back and send a different size. It's years since I did this but I had good results from Field and Trek in the UK.