Mobile phone contracts can tie you in for a year or longer, but Smarty offers a much more flexible alternative if you want plenty of data without making a long-term commitment. Its £10 monthly SIM plan includes 40GB of 5G and 4G data alongside unlimited UK calls and texts.You pay monthly in advance and can cancel or change your plan whenever you want, and Smarty promises no credit checks or annual price rises. You can choose between a physical SIM or eSIM, and 5G access is included at no extra cost with a compatible phone and coverage.Today's best Smarty SIM deal40GB rolling SIM plan: £10Smarty's £10 rolling plan includes 40GB of 5G and 4G data, unlimited UK calls and texts, EU roaming, Wi-Fi calling, unrestricted tethering, eSIM support, and no annual price rises.View DealWhy we recommend itThe combination of 40GB of data and a £10 monthly price should be enough for plenty of everyday browsing, social media, streaming, navigation, and other mobile use without paying for unlimited data you may never need.There's no speed restriction on the plan, and you can use your entire UK data allowance for tethering or creating a mobile hotspot. That could be particularly useful for connecting a laptop or tablet when you're away from your usual Wi-Fi connection.EU roaming is included, as is Wi-Fi calling which could come in handy if the mobile signal inside your home or workplace isn't particularly strong.Price context & historical valueSmarty charges £10 per month for the plan, which gives you 40GB of 5G and 4G data plus unlimited UK calls and texts.The important difference compared with many mobile deals is that the price isn't dependent on signing a lengthy contract. It's a one-month rolling plan with no annual price rises, and you can cancel or switch plans whenever you want.Should you buy it?✅ Buy Smarty's 40GB plan if... You want plenty of mobile data without committing yourself to a lengthy contract. The £10 monthly price, 40GB allowance, unlimited calls and texts, and ability to cancel or change your plan each month make it a flexible option.❌ Skip Smarty's 40GB plan if... You regularly use considerably more than 40GB of mobile data each month or need a large roaming allowance. Heavy streamers may be better served by a larger data allowance. Browse all of Smarty's plans here.The Catch: What to know before you buy Although the plan includes EU roaming, you can't use the full 40GB allowance while travelling. EU data is subject to a 12GB monthly fair-use limit, while usage outside included European destinations requires an Out of Plan add-on.Smarty may also suspend your service if it identifies that you've used it outside the UK continuously for 60 days or longer within a rolling 12-month period. It's intended primarily as a UK mobile service rather than a SIM for extended stays overseas.Shop the full Smarty range of SIM plans