LON-SAT (could be via IAH, IAD, ORD,..) on 21/04
SAT-LAS (Via IAH, CLT,....) on 25/04
LAS-SAT 29/04
SAT-LON 03/05
If this is valid routing then what sort of tax will I be looking at for a Y redemption?
The routing should be fine, however, you will need to book this as two oneway journeys, as you're stopping over twice.
SAT-CLT-LAS will however likely be considered as backtracking, but you'd transfer in PHX.
Taxes should be sth. like 240GBP