Figures for the number of service personnel stationed overseas can be found in Table 1.1 of Tri-Service Publication (TSP) 10: UK Regular Forces stationed location. TSP 10 is published quarterly and is available in the Library of the House. The most recent publication shows figures at 1 April 2009 and can be found at the following link.
The information on tour intervals is not held in the format requested.
The latest available data, as at December 2006, recorded separated service guideline breaches at an average of 10.3 per cent. across the Army. It is hoped that more detailed separated service data will, in future, be provided by the Joint Personnel Administration System.