You should have also had a mail confirming what was ending in you case everything.Look at "your products" in the my Sky app it should give you a end date when you subscription will end and an you can look at bills also in the my Sky app you should see may be your present bill and your final bill in " predicted bllls, As you say you cancelled on 1 April as you need to give 31 days notice you service should end about 1 May.
