I got some from Howes Models in Kidlington, though it is NOT in the model railway section, but in the radio control modelling section, as it is more commonly used in ballasting boats etc.
Hence, you may want to try a model shop that specialises in R/C Models, especially boats.
Another option is from Squires, as they do sheet "ballast". Not sure what it actually is, but it's heavy and not as messy, and if you drop it, you will not loose it.
Hence, you may want to try a model shop that specialises in R/C Models, especially boats.
Another option is from Squires, as they do sheet "ballast". Not sure what it actually is, but it's heavy and not as messy, and if you drop it, you will not loose it.