tsee:
@trig42 considering I'm challenged even trying to post pics up to this site I'm just not game enough to give it a go myself. An electrician might be able to use the existing cable as a draw wire but that might be risky given internally there's no conduit in place just holes drilled in the house framing with the cable fed through during initial construction. I should imagine the bend angle where the cable rises from the wall to feed along the ceiling cavity will be pretty sharp too. I suppose I should get someone in to give me a professional opinion of what realistic options I have, but I'll need to weigh that up against the risk that if I go ahead and something happens to that cat5e cable that is already in place I could be back to a dial-up modem as my only option.
@Cyril7 my first diagram was pretty light on detail. Here is a more accuarte layout though not to scale as my MS Paint skills are on a par with my image upload skills.
Where the ETP is located is there a power point on that back wall there near the ETP? If so could you not just pull the cat 5 back in to the house and put the ont near the ETP on the inside of the house close to a power point providing there is one there