British artillery in 1940 and 1941, that you might need to use against tanks

In 1940 and 1941, there were still many 18pdr guns and 4.5in howitzers in service. As the war progressed, you were less likely to see these in Europe and North Africa as they were replaced by 25pdr gun-howitzers, but in more remote locales, as well as in the local defence role at home, you would still see them. The 18pdr actually could fire an AP shot, although only at about 1,625 ft/sec. With such a gun, you would be looking for side and rear shots against Pzkw III and IV tanks. You would still have a chance with armoured cars, half tracks, and Pzkw I and II tanks. I was not able to get to the actual page, but Google has a cached page with data.