It tends to be dependant on dates & availability. You can get a TravelLodge room for as little as a tenner depending on which one, the dates you want, and when you book, though they are usually between £36 and £52. And a TravelLodge room will cost the same no matter how many people you pack into it. I tend to avoid TravelLodge wherever possible nowadays - the matresses are really squishy (very bad for backs), the heating/air con often doesn't work or is very inefficient, and they no longer have heated towel rails in the bathroom, and the windows rarely shut out all the traffic noise. Plus they don't just give you more tea/coffee/sugar if you ask, you need to bring your own if you want more than their usual meagre offerings or pay some exhorbitant rate for more.
The Holiday Inn price will also probably change depending on date and also, as they provide breakfast, the number of people. It WILL cost you more than travelLodge. It WILL be worth the extra!