(Completely off-topic for the main site, just my own personal thing!)
The whole Man Utd first team fixture list is here, including friendlies, Champions' League, FA Cup and League Cup as well as the Premier League. It's updated hourly, so if you subscribe with your calendar of choice then you need never miss a match, and once a match is over it's updated with the score. Plus it'll automatically carry on into future seasons without you having to do anything.
Tell your calendar to subscribe to:
or if it can't do that then try:
I've set this feed up for my own personal use, so although I'm obviously going to be keen to keep it up-to-date and functional, if you do stumble across it and decide to use it then please don't blame me if it fails for some reason and you miss the Champions' League final as a result! And please don't use it as a data feed for your own app or website. That's not what it's for ...