Just out of interest, where did you get them from? West of England very unusual and lots of problems hatching this year!
I wouldn't shut them in entirely but they will never go into their shed at night without you putting them away so if you want them to be safe from foxes you must always go out and put them away rather than wait for them to find their own way in. What have you got for water? They love to paddle around and play with water so that helps them to relax to begin with and if you put the wheat in the water, they love to eat it that way. Mine love brown bread and that helps tempt them over. Hissing is not at all unusual - you'll get it all through the breeding season from the gander. Also how were they reared? My first pair came from the Chases in Wiltshire who hand rear and were incredibly tame and followed me round the garden pretty much from the outset. My second pair came from Ann Mould in Devon and were far less tame - and still are although much calmer than they were to begin with. Talk to them too - they communicate verbally a lot so they kind of get you talking to them. Just be patient and they will get better although probably never to the point of enjoying a cuddle!
H