Talk to your physician about other extended release options. Vyvanse is designed to peak slowly over about 4-8 hours and trail off the same way, whereas some others use a process of small almost immediate “bump” that trails off after 3-4 hours, then a later bump in about 5 hours from start that trails off in 3-4, then another that trails off by about the 12th-13th hour. The monograph for Vyvanse says that 70 mg is equivalent to a daily dose of about 40 mg of the amphetamine base.
If that works for you, the NHS people should be pleased as well, because there are generics for things like Adderal XR (XL?), whereas Vyvanse generic is some years away. As a comparison, with private insurance in the USA, Vyvanse can cost well over $200 USD per month (depending on insurance, as low as about $25 USD out of pocket), where the Adderal generic extended release may be 1/10th of that with a co-pay/out of pocket cost around $5 per month.
Not talking about what and how much I do or don’t take, but those numbers are what I know about from my insurance.