I get asked every few months for suggestions on where to study Arabic in or near the Waltham Forest area and I have to dig around to remind myself of the options. So I thought I'd up a list of options that I'm aware of and I'll add to this list as I become aware of more options...
Tayyibun Institute - Whitechapel
Since Covid-19 hit, all of the above institutes now offer online classes as well as (or instead of) in-person classes. Another institute which offers online classes which I'm aware of and which has a good standard of teaching is Institute of Linguists. Both Arabic Courses and Institute of Linguists also offer private tuition is you prefer that to a class-based format.
Another option altogether is self-study. If you have the discipline and persistence required to study alone, see this post.