You can work in many places, just be sure they have completed the relevant local authority paperwork to ensure they have assessed the possible risks to yourself caused by employing someone so young. Be aware that there are many rules specific to your age group that will not apply to others.
The hassle and red tape involved makes many employers think twice, which is a shame. The very rules designed to protect workers prevent many from being employed at all, but that's common for everyone of all ages these days I'm afraid!
Good luck!
The red tape doesn't put McDonald's off. The only specific rules there are that you can't work on the tills or in the kitchen, so you'd be restricted to cleaning and lobby work.
You can work almost anywhere that offers unskilled labor: restaurants, warehouses, hotels, grocery stores, government offices (they might put you down as Casual Labor). You can even help friends & family: just charge 'em! *heh, heh* Seriously, ask around town, get some references, see if there are any volunteer projects that have paid positions & such. Good Luck!