OM's deserve to be used with Zuiko glass. The Zuiko 90 is not just a "good" lens, it is a legendary lens. It is not small by Olympus standards, but still compact compared to other manufactures. The pictures from it are remarkable. Wear gloves when handling them, so you don't cut yourself.
You might want check with John Foster over at www.biofos.com for suggestions on getting your OM serviced in the UK.