Replace the horid steel wheels with some 27 inch aluminium rimmed wheels and ride on in happiness. The choice of basic and less expensive simple U section rims vs the more expensive but more durable box section rims will depend on how much the bike is worth to you and how long and aggresively you'll ride it. For basic cruise around enjoying the weather duty the cheaper U section rims will do just fine. If the bike is the sort that encourages more agresive riding shop for a set with box section rims.

There's also the option of switching to 700c wheels and tires. But then you have to check the current brakes to see if they will reach down far enough to catch the slightly smaller 700c rims. If they don't then you need to buy longer reach calipers. Depending on what the bike is set up for currently this may be difficult or impossible. Try the forums Search function with the keywords "700c 27 inch conversion", " 27 inch 700c brakes" or similar combinations for a list of threads. It's one of the most popular topics going and all that is worth seeing on it has been written numerous times already.