Hey hun, are you actually in the Birmingham council area? If so, they have a cloth nappy library so you can borrow some and see if you like them before you buy! This is a fab idea and I wish stinky Stockport council would do the same! https://www.birmingham.gov.uk/cs/Satellite/nappies?packedargs=website=1&rendermode=live here is the link.
If you would prefer your own new nappies to try, this is available on the fill your pants site https://www.fill-your-pants.com/product/55/108/mixed-nappy-trial-pack - you could put your voucher towards this and it would give you an idea about the types of nappy there are available...any you don't like can be sold on easily. There is always a big demand for second hand nappies and you could make a lot of your money back to spend on whicever brand you prefer!
Like dizzy said, the smart nappy system from mothercare is fab, and also most of my stash is made up of those ebay nappies you found! Hope that helps! xxx