Do i get free relief?

My ball was on a strip of gravel that lined the wall that marks the boundary of the course. As a righty I had no swing at all due to the wall and would have to play lefty off the gravel

No free relief. From the Rules FAQ:Q.

I have interference from an out of bounds fence, stake or wall – what are my options?A.

You do not get free relief from objects that define or mark the course boundary. You may not move objects marking course boundaries or take free relief from them like you would from other artificial objects, like a cart path, a building, or a stake marking a penalty area. Your options are to play your ball as it lies, proceed under penalty of stroke and distance by playing again from the spot of your last stroke (see Rule 18.1), or decide your ball is unplayable (see Rule 19.1).

By the way, it sounds like you COULD play your ball as a righty-- just probably not in the direction you wanted to.

Read this interpretation:

16.1a(3)/1 – Obstruction Interfering with Abnormal Stroke May Not Preclude Player From Taking Relief

Hard to determine without a photo, but it seems like it could apply.

The gravel may or may not be an immovable obstruction. It depends on a number of things and more information is needed.

Related question reading this it sounds like you cannot move a white stake marking OB is that correct? Definitely seen and done that before. Ball comes to rest barely inbounds but the white stake is near your stance or back swing. Before reading this I would pull it out of the ground move it and replace after my shot. Seems that would be against the rules?

Yes it is against the rules. This is in the definition of Boundary Object

For the OP, however, it seems that the wall is the boundary object. A gravel area adjacent to the wall, in the General Area, could be classified as an obstruction, but isn't necessarily so, based on this definition:

"Obstruction

(see also Immovable Obstruction and movable obstruction): Any artificial object except for integral objects and boundary objects.

Examples of obstructions:

Artificially surfaced roads and paths, including their artificial borders."

The gravel is processed natural materials, which to me means it is artificial in the same way that concrete and asphalt are artificial. As I read this, its not only roads and paths that are defined as obstructions. If the gravel area is indeed an Obstruction (Immovable), and it interferes with a reasonable swing, free relief is allowed. It doesn't matter that a normal swing towards the green isn't possible, a left-handed swing in that direction, or a right-handed chip out would both be impacted by the gravel under the ball.