The Gamma Charlie Encryption Mystery Cache

This cache is not at the above co-ordinates

I thought it was about time you had a puzzle to exercise the little grey cells
I'll give it a month and then when no-one has solved it I'll add a hint... and then a month later I'll add another one

When you have the final co-ordinates it is a cache and dash
There is an obvious parking spot 50mtrs East of the final co-ordinates
As always be very careful crossing the road

Hint No.1
The puzzle reads Across then Down just like normal text
The solution is a combination of a couple of simple coding methods - but somewhere along the line is a twist !
I'm not including the initial decoding in the above as it is plainly obvious how to begin !

Hint No.2
Something to stimulate those little grey cells

Hint No.3
X marks the spot

Hint No.4
I really ought to be reducing the difficulty rating on the cache after putting all these clues on, but we'll carry on with this months hint.
Vs V unq ebgngrq gur uvag yvxr trbpnpuvat.pbz qb V jbhyq unir raqrq hc jvgu fbzrguvat yvxr guvf