Lebara 3GB - 5p / Lebara 5GB - 85p and 15GB data for £1.14pm for first 6 months, EU roaming, Unltd min /text - no contract. @ MSE / Lebara

If the links in the PO doesn't work, try copy and paste these and remove the * and space after .com:
6p for 3GB: mobile.lebara.com /gb/en/msm/exclusive-monthly-plan-490/p/441174
85p for 5GB: mobile.lebara.com /gb/en/msm/exclusive-monthly-plan-590/p/441175