Hello OP
You should be able to arrange an appointment to speak to a practice nurse at your G.P. surgery to discuss your blood results in detail. You should get a full explanation and be given the opportunity to ask questions.
The NHS doesn't routinely prescribe iron tablets or injections anymore, unless it's been established that you have a secondary condition.
As you are vegan, you may want to seek other ways to improve the amount of plant-based iron rich foods you eat. The practice nurse might be able to refer you to a dietician who can provide advice.
Your G.P. practice should want to repeat your blood tests in 3 months to see if improvements to your diet and OTC iron have worked. You may find it helpful to take iron tablets with orange juice, which would both aid absorption and combat constipation (a very common problem when taking iron tablets, as your poo becomes thicker and darker). You might find one of the OTC liquid versions of iron easier to take and more gentle on your digestive system.
If diet and OTC iron has not worked for you, you may be prescribed iron injections, an infusion or even a transfusion. Next steps vary widely across the country depending on your NHS trust.
If you're still iron deficient after 12 months (4 blood tests 3 months apart), you should be referred to a gastroenterologist and haematologist so they can run further tests.
Some people simply can't absorb iron via their digestive system due to bowel conditions they may not even realise they have. Other people find that infusions (direct into the bloodstream) don't work for as long as they should, so they need them more often.
I hope you get the answers you need and feel better soon 