Let's see:
Liverpool airport -> Blackburn -> Kilmun, Scotland = 278 mijl,5 uur 43 min.
Liverpool airport -> Liverpool Lime Street Rail station-> Kilmun, Scotland = 265 mijl,5 uur 37 min.
I guess it doesn't make much of a difference, except that I suppose Blackburn is a smaller place and thus easier on the traffic. Best thing would be you coming to the airport and I think the second best thing is being on some access road to Blackburn where it's easy to pick you up.