Lots of information and jobs here:
http://www.animal-job.co.uk/jobs-with-animals. html
Pay is usually minimum and the hours are long.
Working in kennels usually involves early mornings, weekends and holidays are usually the times you are expected to work hardest (so forget Friday/Saturday nights out!!!). Often you 'live in' in a caravan and so are on call 24/7.
If you go to work in a rescue kennels you have to be able to cope with seeing animals in distressing circumstances (in the RSPCA kennels you may be expected to put animals to sleep yourself - just because they cannot find a home).
Working at a vets you have to be able to deal with people and animals. How would you feel if someone brought in a dog/cat to be put to sleep? Even if it was perfectly healthy?
Working with animals can be rewarding, but it is extremely hard work in all weathers and can be upsetting.
About the only job I wish I had looked into more was a Farrier, as I love horses and could have started my own business, that way at least you are in charge and can work your own hours.