Having just formed new beds and topped them off with multi purpose compost it’s very soft and fluffy at the moment, should I tamp it down to compact it slightly before i sow or plant into it?
Yes I would if you are planting soon.
Unless compost is soggy wet, we even walk on it sometimes.
Your plants then have firm anchorage.
However if you are not planting until say courgettes in May, the compost will settle naturally.
Thanks Charles, at present two beds are like this with me, one of which is my onion bed which I guess will need to be firm due to the plants involved, the other is my carrots and parsnip bed which I guess will be ok slightly softer?