They will need to be 30 minute fire doors, 44mm thick, which are very heavy, hung in appropriate door linings ("frames") and fire-stopped.
That should have been specified for your building regulations approval. I hope your builder is up to date with fire regulations. They are revised often enough for me not to be up to date. Intumescent pads are fitted behind hinges and locks. You may need smoke strips in the linings, which are grooved for the job. I prefer furry ones which also stop draughts.
It will be an expensive mistake to do work that does not meet regulations.
I got the fake Edwardian 6-panel doors made by Premdor but they make a vast range including 4-panel.
For a Victorian look you will want doorknobs with a long backset latch or lock. Four inch at least. It can be fitted in the central rail which looks best. These doors do not have mortise joints so it will not weaken them. Choose yours before the doors are fitted. Oval knobs are easier to grip than round, especially with wet, greasy or arthritic hands. Modern latches have strong springs. Altro are the best I have seen.
Avoid the fake woodgrained ones because they look fake
They are widely stocked but you might have to order them if sizes (wide range available) are unusual. You should get a better price for a large order.
Example https://www.wickes.co.uk/Wickes-Chester-White-Smooth-Moulded-4-Panel-FD30-Internal-Fire-Door---1981-x-686mm/p/165791
Look at the Premdor website for the full range.
There are several other makers.
I strongly recommend lift-off hinges because these doors are very heavy. Satin stainless are popular, PVD brass look very good but are sometimes hard to get. BZP are cheaper if you are going to paint them.