From your brief description …
I wouldn’t go 6 bed … but I would try and get as many bedrooms with ensuite.
Make the bathroom in the loft a “jack n jill” for both bedrooms… and make the bathroom you have now another ensuite while still creating a bigger family bathroom.
Although, as above, make sure the living area is large enough in comparison to those beds n baths.
Loft conversion are meant to be best bang for your buck BTW … so that’s the right route
I love doing up houses, have started the renovation of the back of mine this week…. Knocking through the kitchen, utility, snug thing, part of lounge/diner and the decent sized down stairs toilet, to create a whacking great big open plan kitchen/diner/living area with kitchen island/bi-folds and … of course …. a log burner 😆 …. The new utility and down stairs toilet/maybe shower room will be taking up part of the vlarge double internal garage.
Will be me doing a fair bit myself …. just the 9m RSJ 😯 , bi-fold/windows, electrics and kitchen install will be by trades…. although its my old man doing the plastering and helping me with other bits.
Good luck OP