as others are already covering the engine replacement side, i'll take a crack at mileage.
i see you are moving from (or already have moved) UK , not sure from which part exactly but i assume could be an area where long commutes are quite common (as it is in australia).. in some instances that 200,000k could have come from about 3 years of commutes at mostly 100kph, in others it could be from 10 years of start stop driving under heat soaked conditions. those long commutes aren't as common here so when we see 200,000km for example, we generally assume it as having experienced greater wear and tear not just running from those k's but also wear and tear involved over a greater number of hours, greater cycle count etc. mind you it's not just the engine but also other parts like gearbox.