This is making me feel quite nostalgic. It's a decade ago since DS started. International Hall, which he found soulless, but which was very convenient. Because students are far-flung a lot happens on campus which is where he made most of his friends. I too went to LSE and went through what was, and probably still is, a rite of passage in the form of a shared room in Passfield Hall. DD had an entirely different experience when she spent lockdown year at Imperial, so no time on campus, indeed her first visit to the bar to meet her peers was after graduation. She loved the course, found IC both organised and supportive, and made instant friends amongst her sports team, so there was a real sense of what could have been.
The big recommendation is to join student societies. DS found sport less accessible. He went to about three football trials and his impression was that the first three teams selected on merit (not him) and the remaining seven on drinking ability (not him either). London Athletic Unions can be very jock-ish. It was fine. A friend suggested he join him in the climbing society at Imperial and he bumped into a UCL student who had been in the year above at school who invited him to join a central based 7 a side team. One good thing about London is that you don't have to travel too far to compete against other Universities. (DD once had to travel to Brighton from Bristol for a match and saw a lot of Wales.)
Some other tips. Sign up for:
https://www.myboxoffice.biz/ which is a seat filling site, offering free or almost free tickets. Discounted tickets can be found through TodayTix and Central Tickets, and places like the National Theatre offer some impressive discounts for students and hold back some cheap tickets for those who queue on the day.
https://www.toogoodtogo.com/ is really active in London. Inevitably there are a lot of bakery items but if you identify a favourite you can get alerts if they have excess food. Look out for ratings, you want 4+. Costa sell M&S sandwiches. I was once given a bag full, enough to feed many hungry students. Breakfast bags from smart hotel buffets can be a good mix of croissants and bacon/sausages as well as baked beans etc.
If you like sushi, Wasabi and Itsu sell food at a 50% discount 30 minutes before closing. Shops close at different times, so worth making a note of what closes when.
The Oasis Lido, an open air swimming pool in central London, is cool. https://www.better.org.uk/leisure-centre/london/camden/oasis-sports-centre
On second year accommodation, there may be some specific student lets but most rent on the open market, so start looking (intensively!) from June on. (One caveat is that the proposed changes in law should make specific student lets a more attractive proposition.) My early tip is to get to know students in other years. If they have a good flat, they might be willing to introduce you to their landlord. Most landlords, assuming tenants reference properly and have guarantors, will be interested in letting directly and avoiding agent fees (effectively 13% for tenant find.) Ditto agencies may be happy not to have to advertise of conduct viewings. DS met some second years via a society who had a vacancy coming up, so he was able to move in, and have the advantage of being with a group studying hard for finals.
Enjoy!