I can't recall ever following a recipe from the BBC Good Food website to the letter but I've always found them a good source of inspiration for my own concoctions.
Here's the Hairy Bikers' sausage casserole:
https://www.bbc.co.uk/food/recipes/great_sausage_casserole_73010
Here's their sausage and ale version:
https://www.bbc.co.uk/food/recipes/sausage_and_ale_82453
Gino D'Acampo provides this one:
https://www.bbc.co.uk/food/recipes/vegetableandbeancass_82705
and here's one from Hala El-Shafie:
https://www.bbc.co.uk/food/recipes/healthy_sausage_16132
My own incredibly simple version is simply to put half a can of baked beans into a casserole dish, throw in some thick gravy to give a meaty flavour, add a good measure of chili powder and put the sausages in. When served with well-buttered jacket potatoes, it's gorgeous!
Alternatively I might start with gravy made with red wine and throw in some vegetable from the packs of mixed casserole vegetable that most supermarkets sell, possibly adding some herbs as well.