Hi Ben,
I know the process from Sole Trader to Ltd Company is create a new account and transfer everything.
While I’m not a QF Genie, or an accountant, I’d imagine the process would be the same, seems you have the option of either when you first set up your account.
In that case - take a look at this thread:
http://community.quickfile.co.uk/t/going-from-sole-trader-to-limited-company/6118?u=parker1090
As always - if anyone knows different, please correct me 