Someone just told me Sherlock S1 premiered on Okto last Friday. Ch5 has aired the first two series back in 2010/11. The Blind Banker and The Great Game will air on 18th April and 25th April respectively. Tune in to Okto on Fridays at 10pm.
If you’re a fan of Doctor Who too, Okto is airing series 7 on Sundays at 9pm.
I’m not really sure myself but the DVDs (and maybe some other merch) can be found at HMV. According to a fellow Sherlockian from a previous message, you can buy some unofficial merch at conventions like STGCC. You can buy them from online stores like Redbubble too.
Mark Gatiss - Sherlock Q&A - Brazil