This is a follow-up to this question.

Let $M$ be manifold (Hausdorff, countable base, finite dimensional, if it simplifies anything embedded in $\mathbb{R}^n$).

I'm interested in the topological vector space $\mathcal{C}_c^{\infty}(M)$ of smooth functions with compact support equipped with the Whitney-$\mathcal{C}^\infty$-topology (The strong one induced by the strong topologies on $\mathcal{C}^{k}(M)$ for finite $k$. Another description for this topology can be found in 4. at the linked question.)

If $M$ is noncompact $\mathcal{C}^{\infty}(M)$ is in general not first countable and restricting to $\mathcal{C}_c^{\infty}(M)$ doesn't make anything better.

Therefore, since I want $\mathcal{C}_c^{\infty}(M)$ to be first countable, I have to make it even smaller. The next attempt is the following: Let $K\subseteq M$ be a compact subset and consider the subspace of functions which vanish in $K$ $$V\colon=\{f\in\mathcal{C}_c^{\infty}(M)|f|_K=0\}.$$ Since $K$ is compact, this should be the "bigger part" of the whole $\mathcal{C}_c^{\infty}(M)$. Now take the quotient vectorspace $\mathcal{C}_c^{\infty}(M)/V$ with the quotient topology.

I reckon that $\mathcal{C}_c^{\infty}(M)/V$ is now first countable, but I did suceed to prove it. Since it's a topological vector space, it suffices to construct a countable neighbourhood basis of $0$. Can someone point me in the right direction?