First of all, congrats on student nursing, I have a few friends who study that and it is hard work!
As you're already out working long hours I'm guessing you'd like to stick to online sources of income? I do A LOT of this to help boost my student learn to I will give you some tips sorted by how much effort they are.
Zero Effort
Competitions - most of them won't give you cash but it can be a great way to try and win other stuff you might need/want e.g. vouchers and make up etc.
Free Lotteries - there are a lot of these available now, they make money through advertising rather than selling tickets like normal lotteries. All you have to do is sign up and then enter draws as often as you like - for some you pick numbers like normal lotteries, for others you use your post code or birthday etc.
Just be careful that you use a legit site - they have no reason to ask for any bank details so don't give them! My favourite one is called free-lottery net, if you have a look at their website they've actually had a few students win decent amounts of money (about £50).
Obviously zero effort means money isn't guaranteed but as its so easy you may as well enter them!
Do whilst you watch TV
Do online surveys - Populus Live and Prolific Academic pay the most and have the most interesting surveys (can get £5-£10 for about 20 minutes work).
Download an app called spare 5 if you have an iPhone, they have fun little tasks which can build up a few quid over time.
More effort but pay more
Sign up to review websites of do search evaluation - search sites online, Leapforce is none to start. They can pay pretty well but you need to actually concentrate to complete the tasks