Are you a FI with Applied Instrument privileges? Because the 800 hour requirement only applies to standalone IRIs, not to FIs with Applied Instrument privileges.
You will need to meet the requirements stipulated in LASORS H1.4 to remove the 'No Applied Instrument' restrictions from a FI rating; these include achieving 200 hours IFR. However, as you will presumably already hold a IR(A), that will have included at least 50 hours of IF; Instrument Flight time counts as 4 times IFR time, so you will already meet the 200 hours IFR by definition.