Everything is as reddy..and delta explained. I think without doubt you will find the JAR 14 ATPL exams the most challenging or onerous. Although having said that, I struggled a little with the airspace differences..and the R/T phraseology..being a country kid from NZ.
From a cost perspective......the flying is cheaper in the north of the UK rather than the south, with your experience it will pay you to find a school that fits your personality..rather than one that promises the earth. The good thing here is that most of the CPL and IR instructors I have had the pleasure to meet, tend to be ex airline..airforce and are thus very competant and experienced.
Be prepared to budget in the region of £20000
cheers
H