You can purchase pure Betaine Hydrochloride also known as Betain HCL containing pepsin. Perhaps this is available in the UK if Zypan isn’t.
You can get a safe one (no bogus ingredients) on Amazon (http://www.amazon.co.uk/Health-Plus-Betaine-Digestive-Supplement/dp/B004JU4WFG/). Remember it’s acid though, so start slow and pay attention to any reactions. Other things that help are eating slower and more relaxed, chewing thoroughly, giving yourself at least 15-minutes to relax before getting up and avoiding excess water before/after eating for 30-minutes or so.