Make it healthier:
Use half-fat crème fraîche, lighter mayonnaise, be good to yourself Cheddar and seeded or wholemeal bread to make these sandwiches.
You could use an ordinary white slice loaf to make these - it will save you a little time, as well as money.
Skip buttering the bread; and use a little extra creamed horseradish sauce without adding the crème fraîche and lemon juice.
Make a caramelised onion sauce to go on the roast beef sandwiches by slowly cooking a sliced red onion with a little butter and brown sugar until it's completely soft, sweet and thick.