For the past 20 years, there has been a UK-wide Summer School for Condensed Matter Theory. It is a two week residential course for which you can receive training credit, and goes into more depth than courses trying to serve both experimentalists and theorist. It provides a great opportunity for networking with young theorists from different universities. It is highly recommended for all first year PhD students in CM Theory, and second year students who didn’t go before.
Additional information can be found here
There is a £1400 cost, with a £500 deposit. For EPSRC students this is ultimately funded by EPSRC. EPSRC previously provided central funding, but now they have devolved training budgets they expect your University graduate school to pay from their Doctoral Training Grant. You will have to discuss the practicalities of this with your local finance office. Bursaries are available thanks to sponsorship from CCP9, inter alia.