Perhaps the OP should try a local GA field first, to see ATC in the raw. If he was to ask at the GA Office Desk he would most likely be allowed to sit in with the A/G radio operator. (and bring him up a cup of tea.)
There he could ask about the Aldis lamp, the LITAS system, and why the runway is called by two different names, and all the other basic stuff before diving into the complicated depths of Heathrow Traffic.
Nearest to Harrogate are Full Sutton and Sherburn in Elmet. Don't go on a wet day as there won't be any GA activity at all, try on a clear sunny day on a weekend.
Freddles.... Have you found the AIP yet? (It has the telephone numbers you require.)