It depends how many times you want to wash them really. Im going to start using them soon but Im only getting about 5 or 6 to start with. Going to use them in the day and then wash them at night ready to use in the morning again.
depends how many nappies you use in one day. at the min I use about 8 disposables. btw some boroughs of London to a real nappy voucher worth around £50.
https://www.realnappiesforlondon.org.uk/
I've started using them recently (although we're still part timers at the moment!). I'd recommend just getting a few different types first and seeing what suits you and your baby before buying loads of them. There are a couple of used nappy sites - I've found some lovely bargains in fantastic conditionx
I use the Bumgenius 3.0 and I love them! We have 24 of them, and it lasts us about 3 days or so, depending if Claire is having a poopy day or not.
I do agree to shop around and find what you like though. I'm lucky that I first went with Bumgenius and I liked them, but not everyone feels that way. Hopefully you find something you like!