I've just bought a (Zebra print) Mobile Tech Appointment Book from Ellisons (cheaper there than Sweet Squared & they seem to be the same - sorry S2). It's an A5 ring bound book, with a plastic cover on the front. Each day is arranged over 2 pages from 8am - 8.45pm, in 15min sections. There is no date, so you can start it whenever you want in the year. At the back there are 5 pages for names, addresses and phone numbers.
However, if you are going to be working a full week (I'm only part time at the moment, due to 2 little ones aged 2 and under), then you might want an appointment book that is bigger. For now, it is perfect for me.