Take a sharp knife and cut down as far as you can between the offshoot and the trunk.
you should then tease out a nice young plant with decent roots.
Pot on in John Innes 3, in a crock pot if possible, with some added grit. Water and keep in a frost free place over the winter. Be sparing with water until spring.

Good luck!

I would be more tempted to keep the propagation until spring as the rising sunlight and temps will help with rooting.

Thank you for your comments Much appreciated.

There are also several shoots coming our direct from the trunk, would this be the same process; do I cut with a slither of the trunk or best to leave these to grow?

First, try to get plantlets from the base - they'll only grow if you can get some root attached. Second, wait till spring, as Kildermorie says. Third, the ones growing higher up the trunk will not grow if you cut them off, with or without a piece of trunk. If you leave them, they will eventually form branches - you may decide there are too many and might want to remove one or two, but again, wait till spring, after you've seen what damage (if any) this winter brings.

Spring it is then, and only from the roots. Thank you all for your prompt and informative replies.