Officially URC TV is streamed by VIAPLAY in the UK, and is available on SKy and Prime. It is, however ?9.99/month.
There is an alternative which is free and quasi-legal.
https://vk.com/video/@rugbyonsofa(Information is from a friend who works for the UK arm of a major anti-virus company)
VK is a Russian streaming site that has agreements with many of the continental, and further afield, tv sports broadcasters to allow them to stream their broadcasts. Officially it is for the Russian Federation, but Russian law allows unrestricted streaming outside of Russia. However not sure that the UK courts would agree!
The streams are virus free, but often they superimpose Russian commentry over the English/French/Italian commentry. They usually appear on the site just before the matches kick-off, and are in HD, if bandwidth, and original signal, allows.
Because of the technicalities of converting to streams they are usually between 5 and 10 mins behind real-time.