The most commonly collected decimal coins from change are the commemorative £2 coins, 50p and the UK themed £1 coins. These have separate pages with links on the home page. For the rest, there is this page, which covers decimal coins under 50p face value, decimal coins that are not seen in circulation and bank of England bank notes.
Current Decimal Coins over £2 face value:
Current Decimal Coins under 50p face value:
Decimal Coins not seen in circulation or demonetised: