Would is on of the helping/auxiliary verbs.
It links a subject to a verb.
"I would go to London next week if I had (had is a past tense, and your sentence is occurring in the future, so use have) the money".
I is the subject which is the doer. "Go" is a verb.
That's all I know, I bet some will explain it too.
-Not a teacher-
- For Teachers