Please advise on the sliding folding doors we want to use them on external 3 x 4m is there a way of waterproofing them? And can these be without wood, just glass?

The only door kits we do which include weather seals for external doors are the TIWI sliding & folding doors.  However it is for timber framed doors only, glazed is OK.  We don’t know of a standard kit for this job, we think you’ll have more luck with a bespoke architectural glass supplier.