There are some good seasonal veg choices on that bbc list someone posted above. Problem is, they aren't available. They're not celebrated, or purchased. In countries such as Italy, they have less choice but better quality and big, enticing displays of it.
You aren't going to see big enticing displays of celeriac, salsify, purple sprouting broccoli, different types of cabbage and cauliflower here, unless maybe you go to a posh supermarket.
In season now are Jerusalem artichokes, radicchio, celeriac etc. I'd buy them. My local supermarket doesn't stock anything like that. It has normal orange carrots. It doesn't even have bunches of carrots where the carrots are smaller and sweeter and have the tops attached. This is why our winter produce is so boring. I could go to the greengrocers but I can only go on a weekend and it is about 10 miles away and I don't choose to spend my time doing that on a weekend.