Saving an old garage - fixing the foundations (water ingress) - advice please!

[VNA]

Not started digging on the left side yet, I can just get a small wheel barrow up there, creating a permanent air gap here will be difficult.





Not started this side either yet.  Whoever landscaped the garden has sheeted the garage, but it's useless, does not work.  Will be interesting to see if I find drainage, but I doubt it.




This is where I am just now.  That's the rear of the garage, I'm down to the concrete base, 3ft down.  The top was chipped, underneath sort of tarmac 1.5 foot out.  Going down - 1.5 foot down of very wet soil, then 1.5 of ash waste, not so wet and much easier to gig, and now back to soil down by the base.  There's a matching 3 foot tide mark inside the garage and water gets in.