I recently took up the guitar and bought Yamaha F310.

The steel strings are tending to put me off playing, although I now have rock hard skin on my finger tips ( with perminent grooves) it is not a pleasent experience having no feeling at the end of your fingers.

Sorry for the waffle, my question is, has anyone had experience of putting nylon stings on this guitar ? any known pitfalls ?

If you want nylon strings, you really need to get a Classical guitar. It's just not good for the neck to put nylon strings on a steel string Acoustic. Your guitar is designed to have the tension of steel strings on it and putting nylon strings on instead would mess everything up.
I had that guitar. And it is awesome considering some of the junk i've been through.

Stick through it, have no feeling in your fingertips for a while, then itd be good.

Trust me, nylon strings = bad idea
Just keep on keeping on it gets so much easier as your fingers form callouses however you can put .010 or .011 gauge strings on it and that will help out as your playing skill and stamina improves you can go up in gauge.
I also had the same guitar, and yeah you won't be able to play perfectly right away so don't worry just keep practicing and you'll seamlessly begin getting used to it eventually... it's the same for any acoustic, so if you really hate the callouses then you'll hafta get a classical haha
It's a steel string guitar. Keep it that way. If you need a softer feel, you could just try different types of steel strings on it. Martin Silk and Steels are one you should try. Also Elixer polywebs or nanowebs. The coating makes for easier fretting. If you really need to have softer strings under your fingertips, then you might have to break down and buy a classical guitar.
Thank you all for the replys, I have now put some lighter gauge strings on