I'm thinking and would appreciate if my thinking is right.. Can I open a new ISA let's say with Santander, then transfer my current ISA (Barclays) over to them before the 6th April (new tax year) then when the new tax year starts top the new Santander ISA up with £5,760?
Firstly you should check to see if the new ISA allows transfers in.
But if you have less than £5,640 is doesn't really matter, as long as you get that deposited into a cash ISA before 5th April. Then after that you can deposit up to another £5,760 for the 2013-14 year.
I've got a 2.2% cash ISA which allows unlimited withdrawals and deposits without penalty, so just in case any emergency crops up, I won't have to wait 60-90 days to withdraw without penalty.
I have another 2 regular savers as well; 4% with Norwich & Peterborough (max £250 per month) and 6% with First Direct (max £300 per month).
It's worth setting up an ISA now, regardless of the rates that are out there.