I have the first issue from 1979 with Tom Baker on the cover. I also have many, many more following issues. Are they worth much. I mean worth insuring?

They're not hugely valuable, though they regularly fetch good prices on ebay. Their value, as with any collectible, also depends very much on the condition they're in (and a copy with the original free gift attached is worth more than one without it). Put it this way: you aren't going to pay off your mortgage by selling them, but don't chuck 'em out, either. There's a good condition copy of the first issue with free gift currently listed on ebay for £16.99, and I sold one a few months back for about £25, but if yours is a tatty copy you wouldn't get that.