hello! i'm a first year at oxford but not studying physics, so i can only answer general questions. it sounds like you're really passionate about your subject, which is really useful! this will help to keep you engaged with your content and motivated when it may feel hard. i would be lying if i said there wasn't a lot of work, but there will always still be time to do other things like relax / join societies / hang out with friends - whatever you want to do! there are lots of lovely libraries that i would recommend you study in as it's quite important to not study always in your room and get out and about. my offer holder day was very lovely - a couple of talks, a tour around the college, lunch in hall and some time chatting with the other people there (i imagine this is quite a universal template for offer holder days). to answer your question about are you strong enough - yes! the tutors are interviewing to find people most suited to the style of teaching at oxford. they interviewed you and obviously found things in you that mean you can do it. you will have moments of doubt but always keep in your head that you deserve your place and no one should tell you otherwise. socially, people, on the whole, are very lovely at oxford. people are friendly / passionate and willing to hang out - never fear and get stuck in. congratulations on your offer, i hope you've taken time to congratulate yourself on your work.