You can go into the F section of the lounge with no problems. There are usually some snacks on that side (crudites, biscuits) and some sandwich/fruit on the Club side. These are separate from the buffet, so I assume are available for all lounge guests, not just CW/F pre-flight diners.

BA98 is frequently late, so if you are returning to ZRH, there is a good chance of missing the connection. Don't panic...the YYZ team are great at pro-actively sorting out the connections and informing you when you drop off your bag which connect you are now on.