Rent arrears and tenants have separated

So, my tenants have racked up quite a considerable amount of rent arrears over the last year altho they have been trying to continue to pay a bit here and there.
Today have been notified that they have separated, she has moved out and he wants to stay currently. They have a joint periodic tenancy currently. I guess she needs to give written notice so I can change tenancy over to just him. Then both liable for arrears still? Not had this situation before, where to go from here to make sure arrears are still recoverable in future if a payment plan doesn’t work out. Any advice very welcome, thanks in advance
Lewis

The NRLA have set up a plan with property redress regarding recouping arrears

Gothard Rowe is another company that specialises in recouping arrears and helping tenants find alternative sources of income ( she did a webinar on Landlord Law on you tube). She applies to charities and other organisations for funds or sees if the tenant can claim more UC

You need to formally surrender the first tenancy and start all over again with a new tenancy contract, inventory, deposit, right to rent, alarm check, serving documents, legionella risk assessment etc etc
If they are significantly in arrears for the last 12 months do you honestly think you will ever recoup that money?
Are they unemployed?
We are amidst an economic hole
Can the tenant that wants to stay afford the property by themselves? ( they can’t afford it as a couple!?)
I would sit down and have a discussion with the tenant as to the likelihood of him affording rent on his own in light of what you have written.

Is it worth calling it a day?

The tenancy can only end for both of them. Either by joint surrender or 1 person serving a valid notice once the tenancy is periodic. There is no requirement on your part to re-contract with either of them and why would you if they are in substantial arrears.