This subject has already been "done to death".
Giffgaff cannot include 101 in goodybags, because the company that operates the service requires a payment of 15p for it -- unlike other numbers in goodybags, which cost giffgaff almost nothing to connect to.
According to http://media.ofcom.org.uk/analysts/regulated-prices/ giffgaff must pay 0.503 pence per minute to connect to a non-giffgaff mobile. So if giffgaff is required to pay the police operator the full 15p then each call to 101 costs giffgaff the same as a 29.8 minute call to another mobile.
It's doubtful that giffgaff could charge for the call by deducting 29.8 minutes from a goodybag, even if it wanted to (and even if it had the technical capacity to implement it). According to https://www.askthe.police.uk/content/Q781.htm Calls to 101 will cost 15p, no matter how long the call, what time of day it is made or whether it is from a landline or mobile phone. So there seems to be no flexibility whatsoever -- calls to 101 must be charged, must be charged at 15p per call, not some other value and paying with an alternative currency (such as 29.8 goodybag minutes) might not conform to the police rules.