tenant rent arrears and possible eviction process

Hello
I have one recently licensed HMO property, with one tenant who has not paid rent for several months, despite all the other tenants paying theirs on time. Most of them have standard 6-month tenancy agreements, but he does not, having just deposit receipt and TDS certificate. They are all now on periodic tenancies.
His initial reasons for non-payment were due to loss of job after being a tenant for 12 months, and promising to bring rent up to date when in full time employment. I have found out that he is now working, but not paying the arrears or new rent or bills either.
How can I ensure I am able to recover the rental and bills arrears, (plus any legal costs) or do I need to serve a Section-8 eviction notice first via a lawyer?
regards
D