GM will have had to exhaust her appeals first [you just know she's gonna appeal everything] and
"be a British citizen or have close family ties with the UK (normally through permanent residence in the UK)".
Is GM even a British citizen any more? I know she's a US citizen, and I'm not certain you can be dual with UK. And she's not a permanent resident. I also can't imagine UK authorities wanting her in the UK. There's already been too much embarrassment over Prince Andrew, and this would create renewed ruckus in the press.
How the British embassy or consulate can help, including contacting family, UK prison transfers, money transfers and complaining about mistreatment.
www.gov.uk