I think that the Isalmic Centre for Cultural Understanding offers spoken arabic courses for beginners. Classes also run from the Trade Centre but I think these follow an academic curriculum. Both are quite pricey, I haven't attended nor read any reviews. Maybe someone else on the forum has.
I took arabic lessons with a teacher one on one before coming here (reading and writing) and would love to find someone here to continue with that. If you do find someone good I would really appreciate the recommendation.
In the meantime I came across this free EU funded resource. Contains everything that you need to get started.
Also, if you check the app store, there are quite a few good free apps. I have one which produces flashcards of letters, words, phrases...to brush up on my pronunciation whilst on the go when I have a spare 10 minutes or so to waste.
I have been studying Arabic in Eton for the last 9 months. I can say I am happy with them, the only problem is people quit after 2-3 courses and then the new class might not be opened due to lack of students.
And although I love it, it is really really difficult.