It's a problem with most vehicles for 1/32nd scale WW2 dioramas, except the Jeep and the Kubelwagen, and maybe the U.S 2.5 ton truck,which can be found as die-cast models. (Good examples are available from Forces of Valour). Unless you get the latter truck, and make a 'bowser' back, I doubt you'll find a good fuel truck, especially a 'British / Commonwealth' type.
Figures can be obtained from various sources, but most I've seen are relatively expensive, and not that good. I normally use the old 'Airfix' Multi-Pose 1/32nd scale figure kits (6 figs per box, normally around £5), not bothering about 'nationality', as they'll be converted. For your purposes, I'd probably use either the '8th Army' or 'Afrika Korps' figures and, if necessary, re-shape the torso to simulate the lack of shirts, although I have seen pics of Aussies wearing a singlet or T shirt !
Other items such as fuel drums are available in 1/35th scale of course, but unless they are placed at a distance form the aircraft or figures, the scale difference is still noticeable. But they can easily be made from suitable diameter wooden dowel, with the grain sealed, and stretched sprue, wire, or similar, wrapped around to simulate the 'rings' and end flanges.