I love these stickers!! Also use their shoe stickers and ones for his cups he takes to nursery https://www.petit-fernand.co.uk/?gad_source=1&gclid=CjwKCAjw-O6zBhASEiwAOHeGxWh2S8MSniKdOP_70gAnRm-ZKafTUWuKjgVrR5aXz1HN9V50QqhTGhoCSfUQAvD_BwE
They don't come off in the wash or drier... But then if you come to give away/sell after outgrown you can peel them off
https://stamptastic.co.uk/?
http://www.mynametags.com are a great option. They stick on to clothes labels and survive great in the washing machine. I tried markers and a stamp, which honestly pale in comparison.