Turbine owners insist on either the renewableuk or GWO Global Wind Organisation SWAH and rescue qual, for the construction, and operations phase. Same all over UK and Europe. The kit is usually stored in a steel box incise the nacelle at the top. It is a single rope system subject to 6 monthly checks. The kits are designed to be used by non frequent climbers and are quite foolproof. Some systems have an abseil type device with fire resisting rope.
Very few farms have specialist expert medical rescue teams, that have specific rope rescue and medical capabilities. The offshore wind farm I work on has several of these teams where I am a team leader.
Info from an H&S specialist (not me)(Via IOSH Website) SWAH = Safe Working at Heights