Angels are in the (seven) heavens, and there is nothing wrong with saying they are in heaven or pointing towards the sky to indicate them. Allah says:
And how many angels there are in the heavens whose intercession will not avail at all except [only] after Allah has permitted [it] to whom He wills and approves. (53:26)
As for Allah, it is possible to say He is above the throne which is above the creation:
It is He who created the heavens and earth in six days and then established Himself above the Throne. He knows what penetrates into the earth and what emerges from it and what descends from the heaven and what ascends therein; and He is with you wherever you are. And Allah, of what you do, is Seeing. (57:4)
It is better to refrain from saying He is in heaven since the heavens are His creation.
But, it is possible to point up to indicate Allah. According to a narration in Sahih Bukhari:
The Prophet then raised his hands till we saw the whiteness of his armpits, and he said thrice, "O Allah! Haven't I conveyed Your Message (to them)?" (Sahih al-Bukhari)