What do you mean by work experience? Do you mean actually working in a bar or restaurant, or do you mean something like shadowing a lawyer or observing in a hospital?
Presuming you’re a British citizen, in order to work in another country (other than Ireland), you would need a work visa.
You can get working holiday visas for countries like Canada, Australia and New Zealand, but you need to be able to demonstrate that you have savings above a certain level to support yourself.