On 2 of the travel days, you can use your pass in your country of residence (inbound/outbound journeys). So yes, you can use your pass from/to your home town.

ONLY if you also use that €star same day!

This trip needs to be fairly direct, no roundabout swings or sidetrips. Due to very high fares and protection of income in britsh trains this is often fairly thoroughly checked-you may be asked for proof for the €star or a flight out. Or at least this is often stated as such in british railforums.

For the last trip home same applies in reverse.