Sólheimajökull glacier is one of the most famous glaciers in Iceland. You can read more about the glacier here.
It is a lifetime experience to be able to join a tour on the glacier. It is nothing like exploring the raw landscape of the glacier with holes and crevasses and ice formation that are changing from day tour day because of the glacier is moving and melting.
During summer the glacier ice is white and some places covered with volcanic dirt. During winter the glacier ice can be blue colour or covered with snow. It does not matter what time you visit you always get to see something interesting and learn something new.
The glacier walk tour is about 3 hours, and I recommend to have good hiking boots and warm and waterproof clothing. The tour starts from a base by the parking and it is about 30 min walk from the base to the glacier then you spend some time walking on crampons on the glacier before heading back.