Grease a loaf tin, a 900g/2lb one is ideal but you can use one slightly smaller or bigger. Line with cling film, then cover just the base with one layer of smoked salmon slices, trimmed to fit neatly.
Whizz the cream cheese, cream, lemon zest and juice together in a food processor to combine. Scrape out and stir in the dill and chives with some seasoning. Spread an 8th of the cream cheese mixture over as evenly as you can. Top with a layer of salmon slices. Repeat with the cream cheese and salmon - you should be able to do 7 layers of cream cheese (By starting with just an 8th of the mixture, it means as the tin widens you'll have enough to put a bit more as you go further up creating even layers.) Finish with a last layer of salmon (and treat yourself to a smoked salmon sarnie with any trimmings!) Cover with cling film, pressing down gently, then chill overnight.
To serve, turn onto a platter and gently peel off the cling film. Scatter with a few dill fronds and serve with lemon wedges and toast.