For the majority of coins it's going to be a case of the condition that they're in, so if the condition is similar to the penny then probably not worth much. Although the 1917 threepence will have an intrinsic value due to it's silver content (.925), but only a few pounds, if that. The 1948 farthings are ten a penny, only a few quid tops and it would have to be in excellent condition even to fetch that.