i just bought some of cpc in preston , (mail order also take switch etc ) they do it on 25m rolls ( normally 100m ) (cb09194), they also do the relay(sw02655) and fuse holders (cp03044) , if you check there site & put these part numbers (all spec comes up on product ) just to make sure the spec is ok for you , as these are only my interpretation of what is needed and have an account at work so it was easier for me than dealing with muppets in accesory shops saying whoo we don't do any that size m8 , must need a big cable for that one .
regards gaz