First of all, if there's any chance at all that you might like to do an Instrument Rating at any point in the future, you should do the ATPL exams, not the CPL exams. If you do the CPL exams and the IR exams separately, you'll be duplicating a couple of the exams.
There's a complete list of schools on the CAA's website. I have no idea which schools do CPL exams - most students prefer to go straight for the ATPL exams for the reasons listed above, so I don't think there's much choice of CPL schools - but I haven't looked, so I'm not sure. I'd definitely recommend Bristol for distance learning - that's who I'm doing my ATPL exams with. But I'm not even sure that they do the CPL exams - you'll have to check.
Also, try posting this in Wannabes (if you haven't already) - most CPL/IR stuff goes in there, so you'll probably get a more appropriate audience.
FFF
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