Nielsen is the UK ISBN agency. The smallest block of ISBNs they will sell is ten. Buying a block of ISBNs sets you up as a publishing imprint. You should take care in selecting your imprint name. Nielsen will try to tell you if the name has been used before, but they cannot guarantee to avoid a clash. I selected Griping Griffin (the name of an inn from a novel I wrote years ago).
Nielsen provides a PDF form online to apply for ISBNs. A block of ten (as of May 2015) will cost you £144. The form is fairly straightforward. It’s an editable PDF form, so it can be filled in on your PC.
Nielsen are friendly and helpful,so call them if you need help. You can pay by credit card (supply the card number on the form or a phone number that they can ring to take payment) or by direct bank transfer (which takes a couple of days to clear).
I’ll try to clarify a few fields:
Publishing Name is the name of your new imprint.
Communication Details. I chose not to show any of the data.
Date of Publication. You need to specify a month and a year as a minimum.
Subtitle. Don’t confuse subtitle with series title (as I did).
Name and address of publisher. That’s you (and your imprint).
Name and address of distributor. This one took me a long time to research. Since I am publishing and distributing via Ingram Spark, all I wrote was Ingram Spark (via Lightning Source). Nielsen understand this and will fill in the correct details for you.
Fill in the payment details, and you’re done.