This is a great bonus, especially during winter when it gets dark so early. To save costs you could dig the electric cable trench from house to shed yourself. Ensure you have an electrician connect the cable, install sockets and light connections.
Adding thermal insulation is sensible if you plan to use the shed year-round and there are products available to keep the shed cool in summer and warm in winter.
When painting the outside think about whether you want it to become a focal point or blend into the garden surroundings. Using bright colours will make it stand out and darker colours the reverse.
Other projects to consider are making a wooden rose arch or rose arbour. Try using sweet chestnut because it’s very long lasting (40 years plus in the ground) and can be put straight into the ground without any form of treatment.