Many thanks to all respondents. Loads of useful info.
The interesting thing is the extreme discrepancy between what most private pilots take to cross water (1 lifejacket of indeterminate age, possibly never serviced) and what you actually need to survive if things go wrong. It's good to hear it from the horse's mouth, but bloody hell this stuff is expensive, innit?!
The dunker course would be useful, but won't make it this year, certainly. I'm a bit sceptical about spare air until I've done the dunker course, but does anyone know of any suppliers of the civvy version?
Also, does anyone have any recommendation for very small, very light liferafts?
Thanks,
QDM