Im planning a trip to Lanzarote with my boyfriend but as i have never been here before i am unsure how much spending money i need , as we are planning to book a last minute trip we have not had much time to save ,.. we are going for a week from january 13 to the 20th , i would really appreiciate your comments , also if u could let me know if the island itself is expensive ... thanks

It depends what you want to do, and where you are staying, but eating and drinking will be a little cheaper than the UK equivalent. Food in shops is a bit more expensive than UK, but beer and spirits are cheaper. Buses and taxis are relatively cheap. So, if you work out what you'd spend in your home town, doing the things you plan on doing, and assume it'll be a little cheaper, you won't be far out.

It all depends on your outlook as to how much you spend. The main thing is to enjoy yourself and your budget.
I have found that if you eat local and drink local you won't go far wrong. Acquire a taste for the local drinks and food and your budget will go a lot further.
Avoid some of the "Irish" bars as they can get the arm in a teensy weensy bit. Likewise some of the cocktail hotspots as they can be expensive for the amount given. Hunt around for promotions on offer, they're there to be found.
Otherwise enjoy the island. It's beautiful, relaxing and full of energy all at the same time.