Hello there,
Cats Protection (the UK's Largest Cat Charity) offer vouchers for Neutering (up to �26) for those on qualifying benefits.
Have a look at this link:~
http://www.cats.org.uk/workwedo/neutering_fina ncial.asp
If you ring the 0845 number they can answer all your questions.Unlike the SPCA their neutering doesn't go by district.You get a voucher which you give to the vet,althought if it costs more than �26 you may have to pay the extra yourself.
Do give them a ring they are most helpful and friendly people.