It would be £329.98 for them upgrades and a new bike I’m looking at would cost £699 or 799 for a cannondale.
Is the frame worth upgrading?
If the microshift drive is working then Nope IMO, just keep it for now, R501’s at this price would be a worthwhile “Upgrade” as would a new pair of tyres, but if the gears function adequately then leave them for another day…
In terms of Cost/Benefit ~£100 on wheels and tyres would be more use to you right now than £200+ on a drivetrain you’re only going to wear between now and May….
like many have said on this thread, maintaining the triban on a shoestring so you have something to ride when the weather is grim and save wear and tear on a possible nicer bike is logical… plus it gives you time to shop about and try a few options for that nicer bike, looking at used options or a bit of self assembly is a good idea too…
£500 and some bodging got me a bike with 105 group/carbon Frame and fork so Cheap and nice can be done with some leg work…
Road bikes are mechanically pretty similar to MTBs in most respects with the possible exception of internal routing and bending your head round taping bars, but if you can spanner an MTB and have a bit of time, you should be able to assemble/work on a Road bike and get much more for your money…