Best service/repair/transform around London ?

Hello

I just managed to buy my dream Land Rover: a 1998 Defender 130 300 Tdi with on 34,000 miles.
As i would like to have it checked, serviced and start establishing a trust relationship with a garage (because I envisage several transformations to prepare it for an expedition to Africa) I was wondering if you could advice me on the good companies in the London area for this please.

Thank you for you help,

Vincent