What you may want to factor into the equations is the 500 hours 2 crew that the JAA need to convert your "frozen" ATPL to an unthawed one. Also, if you look around the CAA SRG's website (I have forgotten the URL) you will see that the 500 hours 2 crew will help immensely in other areas such as the IR.
I am over here about to start the JAA ATPL theory. One thing I have definitely found out is that if a "foreigner" comes here with no turbine time then the grass is not greener compared to Oz. They tend to employ the locals and fair enough too.
If you have an ICAO ATPL with 500 hours the medical at Gatwick will "only" cost £189. Logbook assessments can be done via the website too. Although I have not seen it yet.
Hope this helps.