Put down a thick layer of wood chips (hardwood, not pine bark) and let them decompose for a couple of years - when you're ready to garden again, the soil will have been fed by the decomposing chips and ready to grow whatever you want, and the weeds will have been kept to a minimum.

Don't be surprised if it's a little longer than a year until you are completely back into gardening - I think my girl was close to four before I did more than maintenance. Not because she was so much work to take care of, but she was so much fun to be with that weeding took last place. Enjoy your baby!

Lombill, I think that you should post this in the Vegetable Forum, too.

Crimson cover is an annual, but reseeds easily. Blue lupines are beautiful and add nitrogen to the soil too. Birdsfoot trefoil is a great choice. Comfrey doesn't add nitrogen, but it contributes other nutrients. I'd recommend a mix of plants instead of just one. Any plants you choose will probably need some weeding while they get established, but once they do, they will improve your soil, and look great doing it too.

I don't think I could let it go fallow! Maybe something that wouldn't reseed and be hard to eradicate in the future? I am thinking like cucumbers, watermelon (small variety), other melons, gourds. Any other sprawling, vining fruit or veg. Indeterminate tomatoes can be left to vine on the ground actually. Not squash, which in my experience gets pests. Stick a little bird bath in there or birdfeeder (only use sunflower seeds becoz they are easy to identify if you want to pull them out - the other birdseed mix will just get you more weeds). This will be enjoyable for your baby, even a few months old will enjoy the flowers, fruits, and birds!