What battery do I need mk4 golf 1.9 diesel , Bosch s3?

1998 Mk 4 golf 1.9 TDI.(diesel )

need a new battery had to jump tart it a week ago and if I leave my car 24hours or more it has trouble starting 1st time just whirs. Also there's all white stuff all over the battery which doesn't look so good.

So wondering on which battery for the above model.
Euro car parts seem to have an Bosch s3. For around £65 getting halfords to fit it for £9.99. But with the Bosch s3 it says it is compatible for small cars, older engines. Says nothing about 1.9 diesel. Cant find anything too specific on google to help.

Thanks