Answer for Does anybody know of any accessible locations in Harrow suitable for training?

Yes.
 
Have you tried Carramea Community Resource Centre CCRC) in South Harrow yet?
Fully accessible and on a number of local bus routes, CCRC can hire out at very affordable hourly rates a number of meeting/training rooms ranging from 2 person meeting room suitable for 1-2-1 counselling/interviews to meeting/training rooms holding up to 12 people. Also available to hire on an hourly – rate purpose built training room with 12 computer workstations, interactive white board and Powerpoint projection facilities.
In first instance contact Tony O’Hara, CCRC coordinator ¬†on 020 8423 7000 or e-mail: office@carramea.org.uk