See this openvpn client guide for hh5a....
https://openwrt.ebilan.co.uk/viewtopic.php?f=7&t=279
In answer to your question, as the sky hub is on default 192.168.0.1, you can leave the LAN IP address of the HH5a unchanged at 192.168.1.1 if you follow above guide.
(re. your image. You have set the wrong WAN side static IP address btw)
ps. openvpn client does not use/require uPnP.