Required Text: Randal Bryant and David O'Hallaron, Computer Systems: A Programmer's Perspective, Third Edition, paperback, published in UK by Pearson, ISBN 978-1-292-10176-7.
Recommended Text: Brian Kernighan and Dennis Ritchie, The C Programming Language, Second Edition, paperback, published in UK by Prentice Hall, ISBN 978-0-131-10362-7.
Waterstone's on Torrington Place and amazon.co.uk sell both books.