tummy tub FTW! loved it. used one for all 3 of mine, when the older one was in the bath i put the tummy tub and younger one in with them, great times. only think is i only got about 6/7 mths out of it each time as they got too big and wanted to stand up.
If you are planning more then one, i would invest in a tripp trapp highchair - expensive, but takes up no space, grows with the child(ren), can be used for adults afterwards, and helps, IMO, with their back strength.
I would also invest in a phil and teds from day one if I were to do over, a second hand one is fine, but will be used again and again and again - the one i have I have used for the past 3 yrs, and it was 3 yrs old when i got it, battered but in perfect working order and so versatile.
Digital thermometer - unfortunately essential
Other then that, a few vests, a few nappies, some cotton wool, a few baby grows and a cardigan.
Boobs, nipple cream and a carrier.
some good tea, biccies and pre-made dinners also useful.
Cot, probably, but again if i were to start again, i would not bother until they are older and just co-sleep, sooooo much easier in the short and mid term will get back to you on the long-term. and a proven way for mom to get more sleep.