Ah ok thanks. I'll have a look into it - we're with Octopus now and would be in the new place so I can give them a call and see what the deal is. With/without grant its the direction we'd like to go in if possible, although without the grant it would take a lot longer to get there.
IIRC you won’t get the grant if there’s any other heat source, ie split system with a backup boiler or something.