OK, thanks for the update. It's not going to be easy to sort you out by Forum, unless you can record some stuff, and we don't have your location. Ono-on one would be the best way forward, I'd say; any chance of having a bass-playing buddy come by to check it out..? There may be a willing BC member near you. Sterling basses are fine, so it's only a question of confirming that all is OK, or getting the tiny tweaks of a set-up done. A good music shop might be able to help, too, especially if that's where you'll be buying strings and stuff..!
Hope this helps.
Edit : Ah, I see 'North London'. Open question for the Forum, then... Any BCers from there..? Any recommendations for a decent workshop in that area to sort this out..?
Edit 2 : It might not need a recording, if a Skype session could be arranged.