It's Laurence Fox's first day of rehearsing for a new a play. And he's not happy.

"It's sitting around, doing a read-through and it's terrifying."

In truth, he'd probably much rather be at home, playing his guitar.

Since first picking up the instrument 17 years ago, when he was 20 ("A friend was playing and it sounded really cool, so I wanted a go"), he thinks there are fewer than 10 days when he's not played it at some point.

Aside from Bruce Springsteen songs, which he loves playing, he says he's always preferred writing his own material than playing covers, and estimates he's got about 60 finished songs under his belt.

Selecting the 11 that feature on his recently released debut album, Hidden Patterns, then, was a long and slow process.

"There are some that I now wish were on the album," Yorkshire-born Fox admits. " I put one on what I thought I was the final version of the album, but it's not on there. Caused the record company a great annoyance... But on the whole, they have been very good!"

The oldest of the songs on the album, Rise Again, was written 10 years ago - around the time Fox was first appearing in ITV's Inspector Morse spin-off Lewis.

Despite his acting career, he says he always knew he'd release an album.

"Well, I think I thought I always would. I put a lot of time into it, put it that way, and I had a sneaking suspicion that it would eventually happen. If I want to do something, I normally do it."

Of course, his fame as an actor brought with it preconceptions when he announced he was releasing an album.

"Like anything in life, it's a combination of both things - me being known as an actor both opened and closed doors. 'I didn't know what to expect', is something I've heard a lot, or people are pleasantly surprised when they hear my music," he says.

"I suppose it is weird to switch between things like this. I only really get concerned about criticism from people who haven't listened the album. If someone has taken the time to listen to it and doesn't like it, then fair enough, but if they are prejudiced and won't listen to it, but decide to have a negative view of it, then I am bothered.

"You can't be one of those people commenting on things you don't know about," he adds. "But really, I don't care about criticism because ultimately, I did this for me. I want to share it with people, but really it's for me."

It would be easy to think that Fox would see releasing music as something of a sideshow, a hobby even, with little risk attached. Not so, he says, arguing that the pressure is hugely on with the release of Hidden Patterns.

It's a solid album, full of laments on love and loss, which say as much about Fox's record collection - lots of singer-songwriters, Coldplay and Mumford & Sons no doubt feature - as anything else.

"I am proud of what I have done, and I want people to hear it. I really want people to listen to this, but at the same time, I am relatively private. You don't see me, or the wife nowadays, flouncing around going to parties," he says (Fox has been married to actress Billie Piper since 2007 and they have two children together).

"I am fairly private with my thoughts and emotions, so there comes the pressure, really, putting my head above the parapet. That is the pressure, exposing myself, asking to be judged. Why would anyone want to do that?!"

With privacy so important, is he not worried about listeners reading into his song's lyrics, looking for clues about his life?

"I think if people do that, they will get it wrong, most of the time. But there are definitely enough clues in there. The lyrics are the most important thing to me. You can't have a song without lyrics, so they do mean a lot, and with them being written over 10 years, it's like a diary."

Rise Again, for example, was written a long time ago, about an old relationship of Fox's and sees him telling himself what to do.

"Listening back to those lyrics, I see that I was a lot more courageous then," he confesses. "I am a lot less courageous now than I was. When you have kids, you become really protective and I'd never do the mad things I used to do when I was younger.

"I still have a relatively crazy life, but I am much more cautious. I drive very carefully now, for example. I think 'I don't need drive at 80mph, I'll go at 70 like I'm meant to', and things like that."

He says his music and acting are very much two different sides to himself, with the former being very intimate and personal, the latter more interpretive.

"I realised this morning when I was in this read-through. I'm in charge of my music, as much as anyone can ever really be in charge of anything, but it's my words, my music and so on. Acting is someone else's words, and playing a part, which requires you go to outside of yourself."

Now he's getting back to acting having concentrated on music for some time, he says it feels unfamiliar, but Fox is confident it'll come back to him.

"It's similar to how predictive text has taught me not to spell properly," he says. "You lose an ability, if you don't use it all the time."

:: Laurence Fox's debut album Hidden Patterns is out now. He begins a UK tour on May 17. For further details, visit www.laurencefox.co.uk