Hi Bex - I went through a similar thing when my DD (another IVF miracle!) started daycare. I also work 3 days a week, though she spends the middle day with Nanna. I'm not going to lie, it is tough in the beginning! But you will find being at work keeps you busy and you don't think about them the entire day... just part of it! DD loves her little friends at daycare and learns so much there, it's been so good for her.
The only downside is prepare for the sickness - everyone says it but it's true, your little ones first winter at daycare will be tough but it does build up the immune system! Just make sure you know your sick/carers leave entitlements at work. Good luck!!