Mrs B, the only syn-free bangers are the quorn ones I believe. You can get others for 1/2 (Morrisons Eat Smart or new 8-pk ~Weight Watchers) or 1 syn (Tesco).
However, you mentioned scotch eggs - I did a search on the recipe thread and found this from a kind poster - hope it helps:
Mech’s Scotch Eggs (Ideal for green days)
Ingredients
5 Eggs
Sun Grown-Mediterranean Style Couscous (tesco’s) ½ syn per pack
4 Quorn Sausages (any)
Fry Light
Preparation
Fry the quorn sausage using fry light, let them cool then mash them up into sausage meat (i use a blender for this)
Take 4 eggs and boil for 5 mins or till hard boiled
prepare the couscous (simply add hot water)
Now add the quorn sausage meat and couscous using a fork and mash together, add an egg and whisk in with the fork, again mash these together for a nice consistency.
Frylight a baking tray. Carefully cut the 4 eggs into halves and then cover each piece with the mixture, no need to go daft here just a nice layer to cover all the egg. Place on the baking tray, bung em in the oven at around 180/200 and cook until golden brown, turning once while browning.