Dunno what I've got funny enough Just thought an ISA was an ISA, just that you can only have one in total, and that different banks offer different rates, didn't know ISA's had fixed or variable rates
http://www.moneysavingexpert.com/savings/savings-accounts-best-interest
This guy knows his onions when it comes to banking / savings, the site is a great resource for info on your topic.
Regards