It would seem I should go with a 45, if I can't try them on locally.
Buzzsaw, Sawpit, Taho, Rockhopper & Sonoma Shoe Sizes
Euro U.S. UK
36 4.5 * 3.5 *
37 5.5 * 4.5 *
38 6 5
39 7 6
40 7.5 * 6.5 *
41 8.5 * 7.5 *
42 9 8
43 10 9
44 10.5 * 9.5 *
45 11.5 * 10.5 *
46 12 11
47 13 12
48 14 13
* Half sizes available in some models only