Good to hear from you, bummer about the finish...
I agree with Simon, the only way to fix it is a do-over.
If you're still keen on a natural finish, maybe try something tried and true like Tru Oil. It's reasonably low-odour if you're still only able to work in the house.
Another option is an oil based DIY wipe-on poly with a known/popular brand (don't know if they sell Cabot's in the UK). It can be mixed with a low-odour turps which can make it somewhat more house-friendly.
Sorry to hear of your dilemma. I know the pain of the "guitar finish blues".