reuse slates?

[selfbuildextension]

I am considering sorting our existing roof whilst doing extension so we don't need to touch it again in our lifetime.

Currently it is slate (unsure of type) 1930 built.

If i was to strip front and back, am i likely to have enough to at least recover the front? the back and extension could be different as will never be seen from the front. How much life should the slate have left?

Is it worth the hassle?

 

[datarebal]

ideally better pictures are required, from inside the attic too.
where is the property? county is ok.

 

[Alastairreid]

Scotland and look like ballachulish slate.
The slate may or may not be good enough to save and reuse a slater will advise.