Just stumbled across a nice deal from o2 online for PAYG customers.
If you top up £10 a month, you can have 500 free minutes to one number for 3 months. Bonus is that you can have this as well as an text/ talkalot plan.
So now for £10 a month i get 300 texts and 500 minutes to call the folks
details here
https://shop.o2.co.uk/glossary/N