Craig @ HGFC is pretty efficient, as well as a good and very realistic instructor. Limiting yourself to 4 weeks is pushing it anywhere within the UK though, bearing in mind the amount of groundschool that has to be done as well as flying - 5 to 6 weeks is more likely. Other European FTOs can of course do it rather faster, but I'm not sure how learning to fly a Bonanza relates to teaching PPLs in a PA28 etc!