Hia Fionaplum. I only had about 15 nappies at the start, but washed them daily (with other bits, there was more than enough to make up a load - towels, terry squares that I used under ds when changing, which got either poo or wee on them every time, vests / babygrows which had poo or wee on them......!).
I had about 20 terry squares as a backup, but didn't often need them. Buy lots though, as they are fab for everything - dribble cloths, changing mat liners, towels, flannels and even occasionally as nappies (great if they've got nappy rash and you want to change hourly).
My washing machine is large capacity, and doesn't have a half load, but it is one that weighs the washing and adjusts water / cycle length accordingly. Does yours do this? Mine's a Zanussi.
Is this your first baby? The Tots might seem big at first, but you get used to it. DS was in them from about 15lb. We had size 1's at the beginning. Try buying a few 2nd hand size 1's though - you can probably resell for the same price. MEOS might be a bit better, but we didn't have any of those at the start, so I can't think what they'd be like.
A tip if you want to use your lovely nappies with newborn poo, is to make some liners for them. I've got some cut up flannalette (sp?) sheets which line the entire nappy. It stops any bad staining of the nappy, and they're a lot easier to rinse than terry. We still use them now. Mine are the length of the nappy and three times the width as I fold them to get a thicker pad. You could do the same with muslins, but I find these softer.
HTH, sorry for the ramble.