Spusu (runs on EE) 20GB data, Unlimited min & text, EU & Switzerland roaming - monthly rolling plan + GBP12 TopCashback

SIM only is just that, where you only pay for the minutes, texts, and data you use on your sim-card. You will have to supply your own device i.e phone/tablet to insert the sim-card into, hence why it's called 'sim only'