First of all, there are huge numbers of plants which are poisonous, though not 'harmful' in the sense that the amount needed to be ingested is so great that it would take a very determined person to do any more than give themselves indigestion.
Secondly we raised 5 children with a garden full of these soi-dit poisonous plants and never managed to kill one, or our grandchildren either. Mind we did teach them all that they should not eat anything out of the garden without asking first.
Thirdly, at this time of year all but a few Clematis look like dead twigs, but just wait until spring and watch them shoot. If they are late flowering ones, then you should be looking at pruning them back in early February in any case.
Now, Climbers. There are dozens. My favourites are Akebia quinata, the Chocolate Vine, evergreen but very robust. Lonicera alseuosmoides, evergreen, not spectacular in flower, but a bee magnet with a vengeance. Trachelium which definitely needs a warm fence and finaly Hydrangea anomala ssp. petiolaris which is deciduous but has lovely bark and likes a shady position.
