I'm not an expert, some of our friends from the Gulf should chime in.
A general warning is that, as for western perfumery, the quality varies a lot, also within reputable brands. For instance, I've had wonderful stuff from Al Quraishi, but then also a horrid, hair-raising, and not cheap either, blind purchase. Also, as you probably know, Arabian perfumers work in oil, in my experience, alcohol based perfumes are not particularly good, I don't think the local perfumers have mastered the form. And remember that oils need time to bloom on the skin, they may appear subdued at first.
But you're lucky because you are in London, where I am sure you can find a lot of stuff, at all price levels, from high street top brands to cheaper stuff found in ethnic stores. I know there is an $$$$ Amouage store (for the oils) and an $$$$ Arabian oud store, so you can start from those to get some ideas (I don't know if there is Al Quraishi as well, but there is probably). These would carry top, very expensive oils. Among the ones I've tried and liked, the known Amouage Tribute, Amouage Molook (ambergis), Al Quraishi Cambodi smoked aged oud, and Arabian oud al azerya (which our own orgoglio italiano absolutely loves).
I have spotty experiences with regular priced ones. I like a lot Swiss Arabian Mukhallat Malaki (a powerful synth oud, which has been discussed extensively in this forum) and Mukhallat al Shahama (amber-oud). (Of course, Swiss arabian does the unbreathable Jannet al Firdawsi, concentrated cheap soapy in a bottle.)