Help Please! Tenant giving backword after signing contract last week

Signed Contracts were signed last week with a move in date next week, 15 August 2024. The prospective tenant has paid a holding deposit and security deposit. Not sure about the rent as she’d agreed 5 months in advance upfront. OR will know as they’ve been dealing with it.

I’ve spent a lot of time on this and now will have lost my Open Rent credit plus £40 for 2 reference checks on the tenant and her guarantor. She’s stating a mental health issue as an excuse to get out I suspect? Will I get some compensation or at least keep the holding deposit.

Any advice gratefully received. Many thanks.

JT