Do a search fo LPG in forum titles and you'll find some threads. Link below.
http://www.mini2.com/forum/search.php?searchid=4735488
Being as there is no spare wheel well to house the LPG tank be prepared to lose you boot completely.
Can't recommend anyone in the Manchester area but Chester LPG on Deeside converted my last Rover. At the time they specialised in Rovers but did all sorts. Very professional.
