Change the "Add to cart" button text

// Button text on single product pages (not external/affiliate products).
add_filter(
	'woocommerce_product_single_add_to_cart_text',
	function ( $text, $product ) {
		return $product->is_type( 'external' ) ? $text : 'Add to basket';
	},
	10,
	2
);

// Button text in shop and category listings, for simple products that can be bought.
// Variable, grouped and out-of-stock products keep "Select options", "View products" or "Read more".
add_filter(
	'woocommerce_product_add_to_cart_text',
	function ( $text, $product ) {
		if ( $product->is_type( 'simple' ) && $product->is_purchasable() && $product->is_in_stock() ) {
			return 'Add to basket';
		}
		return $text;
	},
	10,
	2
);