Is it worth interlining ready made curtains?

[kjhkj]

And is it difficult to do? I'm wondering whether I could just unpick where the lining joins the main fabric and slip in in and then add a couple of stitches to secure? Or would this look completely rubbish?

I think it's definitely worth it. I bought some 'bump' cotton interlining and have made an interlined door curtain, it's incredibly warm. I got extra interlining to add to a readymade curtain but it's actually unlined which is annoying, but I was planning to do as you describe .

I’ve done it. It was a hassle to unpick but I could not have bought that amount of fabric for less than twice the price of the ready made curtains. They’ve lasted really well though so worth the effort.