Capt.Biggles,
I reckon you should do them for the reasons Scroggs gives ..... i.e. it a hell of a lot of money to fork out for nowt. At the recent seminars at Gatwick, WWW mentioned someone who'd forked out 30k, couldn't pass the course and ended up with a load of debt. He didn't even get a PPL for his cash.
I did the GAPAN tests back in November as part of the Airtours testing and got a nice certificate to show the Bank Manager when I need a financial "leg up" but it doesn't actually state what level I got but its definately worth having.
The other thing to get your mitts on is a Class 1 medical. That is probably more important than any apptitude pass or fail.
Good luck with the PPL CB.
AF