...servicing?....from Nissan main dealer? 
http://www.nissan-aftersales.co.uk/dealers/fixed-price-servicing ...painful
If you're not bothered about main dealer stamps you can get a service done at a reputable garage for a heck of a lot less
...or if you're feeling brave do it yourself for a fraction of the cost...but this takes time and knowledge of parts locations etc...and the K13 engine bay...looks a little snug
with regards to the key replacement...I think Nissan will want quite a chunk of your soul ^_^
My brother got told that a new key for his Audi A4, from Audi, would be over £100...and it would then cost another £30-£40 to program it to his car <_<
There are Timpson places around that deal with remote car keys that use built in chips...but I don't know how much they charge, again you'd need to buy the key and then have it programmed to work with your NATS system
...you can buy keys from Ebay...but personally i'm not sure about doing that
good luck
