I am very sorry for your loss! You are welcome to post a tribute in our Rainbow Bridge if it feels right to you, and at any point it does so.
Here is our grieving guide if you feel the need make sense of the emotions you are experiencing or would like to look for more resources or support:
Human Bereavement: Grieving, Coping and Support Links for Guinea Pig Owners and Their Children
Sadly most rescues in lockdown are closed for adoptions right now. Good welfare standard rescues (sadly many aren't as anybody can call themselves a rescue without licensing or control) are the best place for your remaining girl to choose her own mate for a happy new relationship, whether that is another sow or a neutered boar. Age and gender come a long way behind mutual liking and character compatibility.
Here is the link to vetted and recommended rescues we can guarantee you are in safe hands. A link to rescues of the same stadnard in other countries is below the UK map.
Rescue Locator
As long as your girl is eating and drinking, she is hopefully hanging in there until rescue dating and adoption are becoming available again. I would recommend to contact any rescues you can get to now.