Your English should be, "In London, is there a good theatre there?" If you specifically give a number to it, then you must have the amount qualifier. If you translate this sentence exactly, then it would be, 在倫敦里, 有沒有一间好的剧场? (as opposed to a movie theater). 在倫敦里, 有沒有好的剧场? = In London, is there any good theatre?"

Long time no see you, Alex Well, It depends on the meaning you want to stress. Translation: 在伦敦有很好的剧院吗？this sentence inclines that whethe there exists good theatres in London, not care about the quantities 在伦敦有一所很好的剧院吗？ this sentence inclines that whether there is one outstanding theatre in London. In other words, in fact, there are more than one theatre in London, but most of them , or all of them are good enough. Anyway, If you just ask causually, no body will take it seriously.both of them make sense。

Hi Alex, The Chinese measure word is necessary to put in this sentence. In this sentence, we will say 在倫敦，有一間很好的電影院嗎? We won't say 在倫敦，有很好的電影院嗎?