4) CPL Flight test - this needs to be done with a CAA examiner but it's possible to do it in the USA at the Bristow Academy. This costs a fair bit - the examiner alone is expensive (around £350 if memory serves) and then there's aircraft hire on top (perhaps £250 depending on type).
Excellent and very informative post BaronG.
Regarding costs, according to the CAA website a
Skill Test for a Professional Licence & an IR Skill Test is £729..