Been to Wirral Country park about half a dozen times now - it's only a 50 minute drive up the motorway from me.
We were there last Autumn until the midday it closed and, were back again this season the midday it opened !!
We're also there this bank holiday weekend, arriving on Thursday lunchtime.
If you DO like walking, drive into West Kirkby and park up. There's a set of 3 little islands in the Dee estuary you can walk out to (takes about an hour each way to stroll, so read the notice boards, they give recommended last crossing times and are updated regularly).
Also - have a wander down to Parkgate. Last time the tide was in here must have been a LOOOONG time ago, as the beach silted up and became covered in grass/ plants! Nice village though - and you could visit the Parkgate horse/ pony sanctuary!
Hope my ramblings help - a little !
Lee.