Do you have any playgroups near to you? Around here there are several run by local churches (although they're non-religious!). They are either free or just cost a pound or two. They broke the monotony of being at home, my child got to socialise with other children, and I met loads of lovely friends, who are still amongst my best friends now. There are usually also free activities at libraries and some local baby clinics.
If there is nothing like that near you, maybe you can make your own. It doesn't have to be large-scale, you can just take it in turns with friends to have everyone round to your home. The kids will love playing with other children's toys, as they are always more exciting than their own! And you can relax (up to a certain point..), have a coffee and talk to other grown-ups.
Other than this there are usually singing groups, which the children love. And going to playgrounds, if the weather is good. (Or even if it is not). If there are no playgrounds near you, how about going walking? You could turn it into an adventure or a treasure hunt, asking them to find things on the way, like a leaf, a feather, or a stone. Biking or scooting anywhere is pretty much an adventure when you're little.