OK. I have made my cheesecake. For the base 8 digestive biscuits and 8tsp very low fat spread. Then I mixed 2 sachets of strawberry sugar free jelly with 1 pint of water and made up to 1 1/2 pints using a combination of fat free strawberry yoghurt and fat free fromage frais. That set ok. Then I topped with a mixture of red berries. In the end I bought some gelatine and added sugar free cordial, a bit of splenda and the juice from the berries to make a glaze over the fruit.
Syns = 3 1/2 syns per digestive, 1/2 syn per tsp marg. and 1 1/2 syns per jelly. Total 35 syns. It should serve 8, so just under 4 1/2 syns per portion. But as there are 6 of us, I suspect portions will be larger, so will count just under 6 per person.
It's in the fridge now, chilling for tomorrow's lunch. Will report back afterwards.