Hi Jack,
I can quite see that you are in a bit of a spot about choosing a convenient camera. In that sense a simple basic point-and-shoot digital camera would be most suitable but they do have limitations.
The Nikon D3100 you are contemplating is a good choice
as it has been receiving rave reviews as an 'excellent entry level DSLR'. BTW, I bought this camera two weeks ago and I am very pleased with the decision. You can spend your free time on board studying this camera and you will be able to learn a lot when using it on auto mode and then experiment with those settings in manual mode. There is a 'Guide' mode that does all the intelligent stuff so if you need to take some quick photographs without putting in a lot of thought before clicking, this would suit you fine.
Your fears of damage is justified and I can only suggest you keep some bubble wrap handy when transporting it.
However you will need to pick up some accessories too and that would include - a UV filter for the lens, a sturdy tripod and a Type C mini HDMI cable available through Amazon for < £10 (to connect your Nikon to an LCD TV). Surprisingly the price of the D3100 in UK is rather steep - almost £100 more than in U.S. and India. Of course they have given you an 8GB SDHC card but elsewhere they give a 4 GB card. The minimum size of a picture would be about 3 MB but you can always resize them to a few kbs.
Nikon has a wonderful website and you should especially check out their Digitutor page which guides you for all their cameras. They also conduct live classes and I saw they charge £149. I enrolled for a four hour course in my city - Basic DSLR concepts - for £3.20 . You can also check out for some tutorials in You Tube.
In my opinion you should go for the D3100 and once you master it you will enjoy photography. I am still about getting the grips but I am certain I will be capturing some great pics soon.
Check out these Nikon websites:-
http://www.nikondigitutor.com/index_eng.html
http://www.nikon.co.in/en_IN/pagearticle.page?DCRPath=templatedata/en_IN/free_format_content/data/custompages/learn_explore/photography_tutorials.xml
http://www.nikonusa.com/Learn-And-Explore/Photography-Techniques/HD-Video-Tips.page
Regards
vin_sun