Its almost like being jet lagged, I have never felt so tired...it does get better, and the best advice I can give you is to listen to your body and it will tell you what to do..
I went to bed when I got home from work every night for an hour, it really helped me and I felt fresh then till bed time.
Drink lots of water in work, keep hydrated and get lots of fresh air
My OH was brillant, he just got on with everything while I rested, so make sure you get lots of support xxxxxxxxx