Traditionally, Sheps Pie shouldn't have garlic in it, but I agree it livens it up.
I put in a stock cube, random amounts of whatever herbs I have to hand, and a splash of Worcestershire Sauce. Because I use 'fake' mince (Quorn or similar) I have to add quite a bit of salt and pepper to spice it up, but if you are using real mince you don't need to.
Tode in the hole is possibly the best British culinary contribution, and is dead easy. Just remember to have the oven hot enough and not to open the door or it won't rise.
Vicky