Hi Suzanne, which carrier are you with? The per-minute cost and add-on options differ depending on the carrier. For instance, Koodo Mobile offers an add-on for $5 that provides 1000 minutes to China, Hong Kong, India, UK, Bangladesh, and Mexico. Fido has a similar add-on for $5 that gives you 1500 minutes to India, China + Hong Kong, UK, Mexico, and Bangladesh.
Additionally, most carriers offer a long-distance saver add-on for as low as $5/month that reduces the per-minute rate to many countries, including the UK.