I found it really hard being away from work, after being so in demand at work it was hard to be at home with a baby and I had PND.
However on returning to work I felt much better. DD was 6 months old when I first went back, I slowly ramped up my number of hours per week so that I could get the hang of it (using KIT days and then annual leave) and my PND started to get better around that time. I have now been working 4 days a week for nearly a year and love it! All my days with my little girl are precious and I have enough of my old life back to feel like me. It is hard to manage sometimes but it is worth it.
Also, I had the same experience as cdwales; DD has never really caused a fuss about me going to work, although she is always pleased to see me and shows me what she is playing with when I come to collect her. I don't know if this is just her nature or whether it is because I returned to work when she was young, but it seems to work.
DD has one day with my mum, one day with my MIL and two days with her childminder and she seems happy with this. The large team of childcarers also means that I usually have someone to cover for one of them being ill or away on holiday so that I can save annual leave for our family holidays.
Work wise, although I am not as available as I used to be, I really do think I am more effective now that I am a mum, because every minute counts and I don't stress about things like I used to. So hopefully you will feel the same.
I didn't really have someone covering for me, I just handed my projects over to various people. I haven't really felt that anyone compares me with the people who looked after my projects. Mostly my bosses just seem pleased that I took the time to properly brief people before I left. If you have done your best then people should recognise that much of the smooth transition was down to you!