The NHS Nightingale Hospital Exeter will provide 200 beds.
It is located at the Westpoint Centre to the east of Exeter (in a nice spot just off junction 30 of the M5 - Exeter Services* are on the other side of the junction); normally this is the venue for the Devon County Show.
* The most southerly motorway service station in the UK.
Meanwhile, there are some nice pictures of the NHS Nightingale Hospital North West (Manchester) here
(now reported as 648 beds).
Also, I hear that, interestingly, there are to be no ventilators deployed at the Birmingham (NEC) Nightingale; the plan being to ventilate patients at the 1,215 bed Queen Elizabeth Hospital, which has 100 critical care beds (the largest single-floor unit in the world). As many will be aware, the Queen Elizabeth Hospital also houses the Royal Centre for Defence Medicine (RCDM).