The default strings on one Gammel Gura is Newtone Heritage 0.12. Or regular 0.11 strings that pull only a few kilos more than NH 0.12.
Newtone Heritage strings have lower tension than normal string sets. You can say that the tension of a 0.12 set corresponds to a normal 0.11 set. The strings have a round core, which means that you should never cut the strings before you have strung them and tuned them up. Otherwise, it may happen that the winding rolls up and you have a string that does not intonate as it should. Unspun strings are the same for both low tension set and regular strings, the difference is the spun strings. Low tension strings have a thinner core and thicker spun string compared to normal strings.
Since the spun low tension strings are softer and vibrate more, you need to have a slightly higher string height than normal on the thick E string and the 12th fret so that it doesn't rattle, my standard is 2.5 mm. The thin E string gets 1.5 mm string height at the 12th fret.
On lightly built guitars or if you still want softer strings, you can use the NH 0.11 set instead (or even 0.10). All sound good, but the volume decreases with thinner strings. I'm stuck with 0.12 which I think sounds good and feels solid and not too thin. Newtone has a web shop where you can buy the strings. I recommend buying directly from the manufacturer.
Here you will find Newtone Heritage strings to buy
Thomann also has a low tension string for sale called Optima Vintage flex. They are similar to NH 0.12 and have the same low tension.
Most of the time I also have Newtone strings in stock, but not always and not of all varieties. What is usually available is Newtone Heritage 0.10, 0.11 and 0.12 and also Newtone Masterclass 0.11. If they are for sale, a set costs SEK 140 + postage. I also have single strings of Newtone Heritage and Masterclass. I try to post as soon as I can, but sometimes it can take a few extra days.