Broadly impossible for me here - the minimum distance for me to get that sort of elevation climb I would put at about 100km. It might be possible sticking within the Wirral area, but is made difficult by the lack of elevation gain throughout and the inability to ride the same road in different directions.
The quickest way would be to head directly into NW and then head up and down around Pentre Halkyn and then come back up the other side of the Wirral - with minimum 30km flat each way to the start of the climbing. @Crackle might have a better idea.
The quickest way would be to head directly into NW and then head up and down around Pentre Halkyn and then come back up the other side of the Wirral - with minimum 30km flat each way to the start of the climbing. @Crackle might have a better idea.