The accommodation and "getting there" information is now available on the Screenwriters’ Festival website on the purple menu bar after the 'attending and paying' page has been selected.
Also, if you are still looking, the nearest hotel to the Cheltenham Film Studios has an online saver special: Travelodge, Golden Valley Roundabout, Hatherley Lane, Cheltenham, GL51 6PN... Tel: 0870 1911701.
It's a bit frustrating for me at the moment because I've got constipated cash-flow this month and what with the expense of Cannes, I'm unable to plan and book for Cheltenham. I'm also reliably informed that "places are filling very rapidly and we do have a maximum cap of 300 so don't leave it too long". Hmmm. Maybe see you there, maybe not, depending on how things go.