I've got swollen tender glands in my neck, but I don't actually feel any other ill symptoms?

Diff possibilities. Tender is usually a good sign & if you have a few relatively small tender lymph nodes you might have mild subclinical allergies or have a cold coming on. However if you have a very lg or hard, immobile node(s) it's best to get that checked out. You might also want to check for swollen lymph nodes elsewhere in the body & if you find some, that would be another reason to get checked out.