Identity cards were scrapped in 2011 - they’re no longer valid and you can’t use them as proof of identify.
You don’t have to return your identity card. You should destroy it or keep it in a safe place.
The fee you paid won’t be refunded.
The government securely destroyed the personal details of everyone who had an identity card.
You can’t use your identity card for travel. Use your passport instead. Contact the British embassy if you’re abroad without a passport.