The first year is a brilliant time of your degree. You have work to do but they start you off fairly lightly so really, really make the most of your free time. Join societies like ArchSoc of course!) and socialise as much as possible. If you can, get involved with some volunteering — the skills and confidence you'll pick up are so useful and in a subject such as archaeology contacts are everything!
Welcome back! Ok, I'm not going to lie to you it gets tougher from here on in — you'll have to work harder and you'll find you know the library and 'jstor' back to front and inside out before long. However it's a great year where you can really start to find out where your interests lie. Once again get involved as much as possible with the department and other people's research when opportunities arise and enjoy it!
Right so I know you've done this all before and you really don't need me telling you what to do, however my key piece of advice — which is applicable to other years as well — is to start looking at masters courses earlier than you think necessary. The AHRC funding application deadline is surprisingly early and some courses have a 'financial condition' which requires you to prove your access to a certain level of money. Details of these are available on the websites of the individual universities you are looking to apply to. I'd also start putting a bit of money aside for the third term. It will be undoubtedly the most expensive term of your degree as every time you go out it will be a celebration!