This is unknown.
The sooner the charity is able to establish the resources and strong relationships with other organisations, that are required to understand the problems and to define, implement and monitor the solutions, then the sooner success will be seen.
There are two key factor that also needs to be controlled in order for the charity to be successful, namely (1) that sufficient numbers of individuals change their driving habits and (2) that these changes are adopted by society at large. Without success in these areas, overall success will be extremely challenging.
Animal welfare organisations have already, successfully incorporated many animal welfare improvements into British society. The charity is therefore confident that whilst the societal challenges are significant (road kill remains an unchallenged issue), these challenges can be overcome.