The yellow lines you mentioned are red,if you stop on them even for just a few seconds the camera van based on the roundabout will snap you and a fine lands on your doorstep, they start front Dunlop road which is the turning on the left just after the premier inn. A lot of people including myself park here instead of the airport car parks whilst waiting to pick up family from incoming flights. The locals a r e in the process of arguing with the airport(peel holdings) to relax or review the parking charges. Taxis get charged £2.50 everytime they pull up at airport and so pass this charge onto the customer.
An alternative would be to purchase a all day all areas walrus card, you can buy them in the airport, get the bus to south parkway jump the train into town and change for the Wirral line.