hmmm how easy will it be to remove the spark plugs from a volvo t5 engine? (alloy head, plugs have been in for quite a while - don't ask but considerably longer than the 30,000 miles )

are they more likely to come out easier on a hot or a cold engine?

Plusgas is your friend and apply it over several days in between journeys

I removed the plugs from a 155k T5 scrapper engine no problem what so ever.

Then use a good wide T bar to get even pressure

Having the engine good and hot often helps