Therion like bands

I bought Gothic Kabbalah listens to it now, wonderfull music, what others of theirs albums should I investigate and are their other bands like them (ok Ayreon are obvious and I already have 01101110110) but like Opera and prog metal in the symphonic weine

I don't think "Gothic Kabbalah" is a good representation of Therion's work. It lacks much of the chorale and orchestral elements which defined their best albums. If you are particularly impressed with GK,  you may not be as taken with the bulk of Therion's output.

Other metal bands that blend with operatic and / or orchestral are Nightwish (specially before Tarja Turunen left the band), Within Temptation, and if you don't mind Growling: Epica, After Forever, The Gathering, Haggard, and perhaps even Tristania; well, even if you don't like growling, you may find enough non-growlers in their albums to be satisfied by choosing the songs. Now, if you like the Orchestral / Operatic blended with rock, even if it isn't metal, you might just as well like some Rick Wakeman albums too, specially Journey to the Center of the Earth, Myths and Legends from King Arthur and the Knights of the Round Table, and Return to the Center of the Earth, plus the new live recording of 6 Wives of Henry the VIII. Other albums with operatic choruses, but no orchestra, from Wakeman are Out There, and Can you Hear me? Plus the song Judas Iscariot (from Criminal Record), and some songs from Phantom Power.

Lacrimosa?