There's optimal, there is suitable then there's convenient. You have to make your own decisions about what's important, like do you drive 2 hours to save £20 an hour on plane rental? Can you live at home or do you need accommodation? Can you train in vacation and weekends and keep your job?
The biggest money saver is getting everything done in 200 hours which means CPL last.
The next priority is cutting down (unnecessary) SIM hours, using real loggable flight time for IR training wherever you can.
Then study the requirements for each module: An MEIR requires 15 hours MEP, but as an add-on it only needs 2 hours, if you have an MEP rating you only need to do the CPL in an SEP etc...
Then study the prerequisites for each module: 70 PIC for MEP, 50XC PIC for IR ect... then you can order them correctly, filling the gaps with hour building.
Then compare, contrast and cost all the options and the most optimal (or suitable) will present itself.