SORTED!!! :L
Have installed new switch, and yes it was fairly straightforward.
For anyone who's thinking of doing this themselves then read on... The new switch comes fully extended. The switch is on a ratchet within the housing and can be pushed in or pulled out to set the correct length. You shouldn't need to push or pull the switch initially. Just fit it in and then the brake pedal, when depressed, will automatically adjust the switch to the right length.
Thanks for all the help & suggestions
Matt :woot: