Tesco operate fairly differently to other companies on their pay as you go sims; instead of offering you tiered top-up perks, they give you complete freedom to choose how you pay. If you top up £10, they’ll give you £20 of extra credit for use on texts, minutes and data for the next 30 days, meaning that your top-up in itself is a perk. You can also contact them for packages of either data, minutes or additional texts from £5 for 500MB, £5 for 150 minutes and £5 for 5000 texts to last you the rest of the month.
Tesco Mobile’s standard rates are 10p/MB, 25p/minute and 10p/text. These rates aren’t super low, but with the extra credit that you’re given when topping up they go a lot further than you’d expect.