So I can save myself ~£100 on a WTP ticket by doing an open jaw JER-LGW/LHR-MCT-LHR rather than going straight from LHR but is it worth the risk?

Once I factor in rail travel, positioning flights (flybe from SOU, which is at least easy for me to get to) and a national express from LGW-LHR it only saves me £30 but of course I get a few more TP, get to visit JER (never been before) and get to fly a Dash 8 (never flown one before).

I'd be looking at getting a 10:50 from SOU, arrives 11:35 (BE241). My JER-LGW departs 15:35, arrives 16:40 (BA2773). Then depart LHR at 19:55, all on the same day.

I also have a flight departing MCT on QR the same day as I arrive (arrive 6.25am, depart 17:55, QR1127)

Is this just crazy? Am I asking for this to go wrong?