When I was 16 I lived in Kirkby and worked at the Iceland in Old Swan, used to cycle there and back on a Friday evening. If I was cycling from the Swan to the Estate in Kirkby, I'd go down East Prescott Road to Page Moss/Woolfall Heath, cut through on Woolfall Heath Avenue, left onto Seth Powell way, over the M57, down Knowsley Lane past Knowsley Village and take Ormskirk Road then cross the East Lancs into Kirkby then into the Estate.
https://www.google.co.uk/maps/search/maps/@53.4467614,-2.8512476,13.5zTrain is a no go, the only line involves going into the City centre, getting the Northern Line from Central out to Kirkby station then getting to the Estate. Its a long time since I lived in Kirkby, but there wasn't a proper bus that went to the part of the estate where the Matalan is, they all mainly went through Westvale and Southdene.