Most unlikely, unless there has been a history of high risk flooding, Bewdley or Upton on Severn for example. The scale in Somerset has been unprecedented there, so unlikely to be a £1000 or more (unless localised history).
Agree with you about the appalling attitude of aintforever, although I'd look at central costs dealing with clear up rather than just compensation for the sake of it. That might start an acceptable precedent. Can you imagine if the River Mersey breached its banks ?
That's not to say the excess for flood might not be increased come renewal.