Apple,
Both sets of students get the same instructors for the ground school and the flying.
The price difference comes from the fact that as Modular you already have a PPL therefore dont need to go for a nice jolly to the states to get it.
I found that there was no distinction in the level of service you recieved. The two groups are run seperatly, by that I mean that there are seperate offices but I am sure that this is purely for admin purposes.
The Mod ground school costs £5450 as for the rest call Dena Dove on 01865 840334, she's really helpful and will get you the answers you want (Dena is the Modular secretary and is a diamond!)
If you have the required hours take the Modular route (unless you want to spend time in the states!!!)
Cheers
TBL