If someone you know has had treatment, their recommendation is useful, but it’s best to do your own research as well. Go online and find reviews of various clinics and various doctors, because the best way of finding out who’s good at these things is to find out what previous patients have said about their experiences.
Make sure you visit independent review sites, such as iwantgreatcare.org and privatehealth.co.uk, which reflect patients’ true experiences.
Choose a clinic that just does veins, has been established for many years, has carried out thousands of treatments and openly publishes treatment results (including side-effect rates).