How long was the scaffolding erected - was it for 6 months or is it just your dispute that has dragged on for six months?
As others have pointed out, if the work was required for the LL to carry out his repair duties, then you have no case after the fact. However there could be a case if the scaffolding was there longer than necessary or reasonable for the repairs.
Also it is an important principle of contract law that you can only be compensated for actual loss, compensation for lost profits is not usually available - so you would need to have excellent proof that your business suffered an actual loss. There has been a exception to this however (in the case of the MI6 spy Blake and also the Jimi Hendrix Estate case) where the party in breach makes a gain on it, they can be made to pay an amount equal to what should have been paid to you in order to vary the terms of the tenancy (in this case the implied covenant of quiet enjoyment). This has only been successful in very exceptional circumstances though, pretty unlikely here as it doesn't seem like a blatant breach (if it is a breach) for profit.
If you had spent money on extra street cleaning, on signage, extra advertising hoardings, etc then this would probably be more easily recoverable as actual loss, but the court would be entitled to conclude that you should have taken action at the time - i.e. by seeking an injunction against the LL to remove or mitigate the scaffolding.
From the facts you have given, you are probably going to have to put this one down to experience. At least presumably the building now looks better for the work?
If it sounds like I know what I am talking about........I don't.