Mike
I started my digital listening to exactly how you are starting. And fully agree with Chris why not simply start with a lead from your headphone output of your laptop to a spare line input on your Naim. Just search on ebay or amazon etc for '3.5mm to 5 pin naim'. I just did a quick look and see many from around £6 upwards to £15. Maybe you already have such a cable.
Then simply use one of your spare inputs on your Naim.
Then stream from wherever you like to get a feel of the sound and controls. Try BBC Radio, Radio Paradise etc. Thousands of free streaming services out there. And suggest you start off with Spotify Free first off. Even though slightly less quality than the paid version the sound is still very good.
A neat thing about Spotify is that you can use your smart phone to remotely control Spotify playing on your Laptop. Live the life of a couch potato.
Later on you can buy a DAC which will lift the quality even further from what will anyway be quite good.
I've done exactly the above for several friends and without exception they have been amazed at the world that has opened up for them.
Current: [P20] Roon/Tidal > Custom PC> Chevron Paradox NDF16 > Phast Pre > Neuro. 686 > Tannoy Berkley (RFC tweaks)