There are other UK quilters on here thata can lead you in the right direction. All the posts I've read make it sound like quilting supplies are very expensive for those of you not in the US. It should remind those of us that are here not to complain so much.
As for here in the US, I bought a beginner set that included an 18 x 24 inch cutting mat, 3 x 18 ruler and rotary cutter at a Joann's for $30. My square rulers came in a set from Wal-mart. 12.5, 9.5, 6.5 and 4.5 inches for $25.