On the outward leg:
1200 Cheltenham Spa- Bristol TM 1242 £6.20
1245 Bristol TM- Exeter St Davids 1343 £11.20
saving £5.80
On the return leg:
1624 Exeter St Davids- Taunton 1650 £5.60
1651 Taunton- Bristol TM 1724 £11.90
saving 20p on Romilly's second suggestion, with the aforementioned £11 ticket from Bristol to Cheltenham.
Using all other splits suggested by Romilly, this gives a total fare of £152.90.
--- old post above --- --- new post below ---
*Bumped owing to potential importance to the OP*
This may be a little late, but Romilly's £15.70 northbound fare between Cheltenham Spa and Wolverhampton appears to include a non-reservable London Midland connecting train to Wolverhampton rather than the Virgin through train to Carlisle.
The three minute connection onto the Virgin train is not a booked connection, meaning that there is a possibility of being stranded at Wolverhampton, having missed the last train of the day to Carlisle.
The ticket is routed 'XC & Connections', so there is an argument that, *if* there is no reservation coupon specifically tying the OP to the LM service, then he/ she may contractually use the Virgin service as a 'reasonable connecting train', on the grounds that the internal 'may not use reservable connecting services' rule does not form part of the contract for travel, although he/she may face considerable hassle using the ticket in this manner.
If there is a reservation coupon specifically tying the OP to the LM service, then even this argument is no longer tenable.