Tim,
Have you looked at the AW list that comes with your portfolio and rung any of the AW's? I'm sure most would be happy to talk thinkgs over with you. If you want monitored 'practice' get yourself on a park cull or out on some stalks - several people/companies in the area you've called out who do this sort of thing on a regular basis. Places like Sparsholt or Lackham Colleges do gralloching days - not quite sure what the content is, but a;so perhaps worth a look. As 6p says, get out there. Remember there is no right or wrong way - just safe and hygienic ones. Don't get too wrapped in process.