PAYG from Tesco is good value, and the customer service is better than you'd expect.
My Australian BiL has one for his annual trips, it keeps live during months of disuse, and when he lost his phone, the desk in the supermarket arranged a new SIM with the same phone no. as he was able to pass their security checks.
When somebody recently died who had a mobile Tesco phone, I kept paying it for a couple of months so I could answer and inform any callers or texts. When I notified Tesco they stopped billing, ran the service up to the end of the month, and wrote off the outstanding balance on the phone.