definitely need 17mm ply at the least or your T-nuts will protrude , especially after tightening with the holds, you can get 18 or 19 mm marine ply sheets, just check the sheet size as marine ply seems to come in 2440 x 1220 rather than the standard 2400 x 1200
a few horizontal wall plates attached to you house wall will allow you to tie the climbing framework back to the house
cheers |