Having just looked at your Trek online, you are wise to stick with it for the time being.
Assuming I've got the right bike, it has a rigid fork which is good - a suspension fork at this price point adds nothing other than weight.
You've correctly identified two things.
Your new bike - assuming you pay £750+ for it - will be lighter, but equally that extra lightness won't make a great deal of difference.
Put another way, if you were after a hybrid on a tight budget, this Trek FX on clearance from
Evans would be a good buy.
https://www.evanscycles.com/trek-7-3-fx-2016-hybrid-bike-EV217060