The lost foam method is quite popular- a lot of members on here have used that technique to build hulls. It's quite economical, because you use very little material in construction, and foam is light and easy to work with, and inexpensive compared with most woods.
It's best to use the higher density blue or pink coloured foam, the polystyrene foam that you get in packaging is too soft and doesn't work very cleanly. Polyester resin dissolves polystyrene foam, epoxy resin doesn't. If you want to stick with polyester resin, then you can paint the foam with oil or emulsion paint or polyurethane varnish, which acts as a barrier coat.
Another alternative is to use polyurethane foam, which is the yellow stuff used for insulating lofts and also comes in aerosol tins for filling gaps in walls around pipes. You can use polyester or epoxy resin straight over this foam.
The sheets used to insulate lofts tend to be filled with glass, so wear gloves when sanding otherwise you'll be itching until Christmas.
I have used polyurethane and polystyrene foam for making hull masters, I skin the foam with a layer of resin and matting for strength, then finish with polyester filler. However, I then make a reverse mould from this, and cast my hulls conventionally. It's more work, but you can produce more hulls if you want quite easily and spares if required.
If you haven't praticed any of these techniques before, I advise you to learn on something small first. Perhaps you could try carving the turret for the Surcouf, being a relatively simple shape and small at the scale you will be working at. That way if you make a hash of things, you haven't lost too much.