I don't really do any prep! The only thing I do is organise a small gift for the other women in our lives (my mum, MIL, grandma etc) and I always get them photos of the kids or some other personalised small gift.
Now that the kids are a bit older they love to make cards and there is a kinder afternoon tea today for the mums which I'm sure will be gorgeous (according to DD I'm getting something very special lol!).

This year we are having DD's family birthday party on Sat night so I think we'll just chill on Sunday! I try to make it less about the gifts and more about spending time together. Honestly I'm happy with a card and a 'I love you' (oh and a yummy breaky doesn't go astray lol!)