Cheshire Oaks aint far away at all, only about 10-15 minutes further up the motorway, just come off onto the M53 signposted for Birkenhead (so thats the second M53 turn off as the first heads into northwales). As you round the joining road the junction you come to is for the cheshire oaks.
Decent place to walk around, the main section has shed loads of shops and its good prices too, on the other side of it theres the leisure side, some decent cheap restaurants, cinema, bowling etc.
I live just down the road from it, nice and handy for shopping
Knowsley safari park would be a fair way to go for just a few hours spare!