Those who are within striking distance of Royal Holloway (Egham, Surrey) might be interested in their annual Science Open Day.
A wide variety of hands-on activities will be taking place across the campus and in all our science departments. Visitors of all ages will find plenty to try in Biological Sciences, Computer Science, Earth Sciences, Geography, Mathematics, Physics, Psychology, and Science Communication. This year's special theme will be Gardening for a Green Future, with displays of work done by local primary and secondary schools, and our own staff and students, on ecology in action. We want to share our ideas for preserving and nurturing habitats that support a diverse range of the plants and animals native to this region. We will also be looking at state-of-the-art composting and recycling technologies.
Most of the activities are for 11/12 years upwards (and adults), but some are also available for younger ages.
They have a website here - http://www.rhul.ac.uk/science-outreach/open-day.html