Is there a way to display/group accounts on the home page in a way that I define?
I've tried categories but it was not really doing want I would like, but maybe I have misunderstood categories!

You can promote accounts by tagging them as "preferred" but I would like to list them in groups, something like:

Main (=Preferred)
--- Current
--- Savings A

Short Term
--- Savings B
--- Savings C

Medium Term
--- Fixed Term Savings A
--- Premium Bonds

Long Term
--- Fund A
--- ISA A
--- ISA B

Pension
--- Pension A
--- Pension B
--- Pension Current