Greart advice from everyone on here and I appreciate you all takng the time to chime in. I'm comfortable now that I can wind at the bottom of Isis lock, come back up and moor. If it's too busy to moor then heading back towards Banbury and taking a train might be an option as Athy says.
We're hiring the boat not from friends/people we know but from a couple who have been privately hiring their narrowboat for the last 5 years or so. They did request an itinerary of names/ages etc from me to satisfy the requirements of their insurance. Beyond that I haven't asked about licenses etc if I'm being honest.
In terms of the Thames I'm going to run it past the boat owners to see if they're OK with me taking the boat on the river and if their insurance covers it. Perhaps if I make good time getting into Oxford I'll head up Sheepwash and onto the Thames for a while.
A few last questions if you'll endulge me...
Is there likely to be enough room to turn my 62' boat at Port Meadow to head back down Sheepwash?
Or alternatively, could I pay the Thames day fee at Godstow lock and carry on up to Duke's cut to rejoin the Oxford canal heading North back home??
Is it difficut to moor on this part of the Thames should we want to stop for a couple of hours, eg shallow banks etc? Do you have to pay to use proper moorings on the river?
Apologies for the barage of questions here but I like to know what I'm doing in advance of getting there when the panic sets in!