£75.40 for an off-peak return
No. This is the fare for an Off-Peak Return (SVR) Kings Norton - Kirkcaldy route Any Permitted with a Railcard. The OP does not mention holding any Railcard, but quotes a fare (£115) close to the undiscounted SVR (£116.20).
if you are not traveling via St Pancreas ...
If traveling via St Pancreas ...
Routeing Points for Kings Norton are Barnt Green and Birmingham Group. There is no Permitted Route from either to Kirkcaldy via St Pancras.
I am planning on travelling weekly on a Friday from Kings Norton to Kirkcaldy and returning Sunday afternoon/evening.
If this is to be a regular weekly journey, Advance tickets may offer you better value. The best deals and best splitting points may vary from week to week.
This week, for example, look at TPE's offer of
25% off Advance fares. This could help you between Haymarket and Manchester. Book by Sunday. Travel up to and including 18 December 2011.
See also EC's
£25 First Class sale. Book by Tuesday 18 October, travel between 3 November and 16 December. This may help you between Kirkcaldy and York.