You don't need a MAC code
if you switch to a Full
But it is always prudent to request one from the Partial LLU
ISP you are leaving, so they are aware you are not ceasing the BB and maybe to fit in with their notice terms, so as to avoid unexpected after-the-event charges.
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC