yes just put sim in.
if sim gets damaged or need different size click here. https://giffgaff.com/profile/details#simswap
number will remain and credit etc
Yes of course you can providing the sim card is the corrct size.
If the sim card is not the correct size you will need to do a SIM SWAP you will need a spare sim to do this.https://giffgaff.com/orders/mgm
SIM Swap allows you to transfer your giffgaff number to a brand new SIM card including existing goodybags/gigabags and airtime credit.
To perform a SIM Swap:
If you have an active PAC code on your account then the link above will not work for you. Instead follow this link to perform a SIM swap and proceed from point 3.