They have most of the same breakfast sandwiches on muffins and bagels instead of the biscuits, but also they have a bacon sandwich on a sub roll sort of thing with brown sauce (or the one at Heathrow airport did, anyway). DH got the Big Breakfast thing last time we went and it looked abysmal, he said it was totally rank. It was a dry "English" muffin, some nasty looking scrambled eggs (probably microwaved or something) a few straggly, ridiculously thin bacon strips, a sausage patty (they don't taste the same in UK - a lot more bland than the ones in the states to me) and a greasy hash brown patty.
The only things I ever liked at McD's for breakfast were the sausage biscuits and breakfast burritos, so that sucks for me! I had a bagel with jam last time I was there because nothing else looked good.