O2 10GB (20GB w/Volt) Data, Unlimited Mins & Texts, EU Roaming Monthly rolling plan £12 TopCashback / Get 120GB for £12pm

There are some more monthly rolling plan.
If you need more data, there is 250GB for £15pm
If you need less data, there is 10GB (20GB with Volt) for £7pm
O2 Priority included
Go via Topcashback and earn £12 cashback too
Tariff information
The minutes and texts included in your tariff can be used in the UK and when roaming in our Europe Zone. Inclusive minutes can be used for calls to standard landlines and mobiles, but not special numbers (see below for more details). Picture messages will cost you an extra 83p per message.Subject to Annual Price IncreaseMonthly price of your Airtime Plan will increase by £2.50 each April, except Data Only and Smartwatch Plans which will increase by 75p. Out of bundle charges increase by 5% every 1 April.