Best thing by far was our three-sided cot. I can't express how great it was!
The bottom line is it bought us more sleep - priceless!
We didn't have one with DC1, he was in a bed-side crib, and it would take a while to settle him back into his crib after night wakings. Also I tended to feed him sitting up, which meant I woke up fully.
But with DC2, she was in a three-sided cot. It meant when she woke in the night I could feed her lying down, and transfer her back into her cot without waking her, and having to wake myself up fully, getting her back to sleep. Or, if she fell asleep next to me in the bed that was fine too as I didn't have to worry about her falling out.
They're quite pricey in the UK, but, following a tip from mumsnet, I bought the Fabimax Rolloway from German Amazon, which IIRC worked out at about £110 for the cot, a mattress, sheets, bumper and delivery to the UK.
You can log into German Amazon with your UK account, and if you use Google Chrome it should translate the page for you.