I think that within most policies, there are exclusions for such procedures, unless there was a medical reason for it? The simplest way to check would to be read your policy though! :)
-Kay
It would depend on your insurance, but I wouldn't think you could get away with claiming for it, unless there was a medical reason, eg pyometra.
Are you on any benefit? I only ask because some animal charities, eg PDSA, RSPCA, SSPCA, will help towards the cost of speying, if you ask them.
Some vets will also let you pay up over a few weeks, if you explain to them that you are a bit short of cash just now, but it depends on the vet. ;)