I don't use GW brand glues, but is it a real plastic glue? Because real plastic glue actually chemically melts the plastic it is applied to and fuses it - so functionally what was two pieces of plastic become one piece.
Superglue just forms a bond that adheres them, and will be much easier to separate.
If you used plastic glue I sort of suspect the only real solution is a razor and some patience.
Also, according to a bit of Google-fu, on plastic models, be *extremely careful* with acetone nail polish, because that will damage plastic. It is suggested to use acetone free glue for cleaning purposes - and it appears to work well with super glue, but no real commentary on plastic glue.