So you're off to Cambridge. Best of luck. This brief guide is an attempt to give you a sense of what's involved in living and working at Cambridge. I've included topics in no particular order, as they've come to me.
WHERE TO LIVE
Depending on where you work, you'll probably want to live in Petersfield,
Trumpington, or Castle Hill. East Chesterton or King's Hedges are good if you
want to be close to the science park, but not much in the way of neighbourhoods
and rather poor if you want easy access to the rest of the city. Romsey Town,
where I ended up living, is okay if you're commuting to Addenbrooke's Hospital
(though Trumpington is even better for this) but lousy if you have any regular
business at the colleges, nearly all of which are on the other side of a very
congested and pedestrianised city centre. The section of Romsey just over the
railway line also is home to some rough characters, though if you're used to
London these people are rather tame in comparison to some that you'd find in,
say, Camden Town. Romsey does offer the advantage of cheap, student-orientated
shops and cafés, although these are not as vibrant as you might expect,
since most of the student life takes place within the colleges. If you like the
idea of Romsey but can afford to live a bit closer in, you might consider
Petersfield, which has better pubs and is on the near side of the railway line.
I ended up living in Romsey because I made a quick decision. If I had it to do over again, and I were constrained to live in Cambridge, I'd choose Trumpington. Although Trumpington is part of the Cambridge city local authority and is closer to Cambridge city centre than, say, Romsey or King's Hedges, it retains many of the advantages of a country village: where else could one be a ten-minute cycle ride from the city centre and from Addenbrooke's, a five-minute walk from a Waitrose and several good, quiet pubs, and still in the midst of so much open space, including the fields around Addenbrooke's to the east and Grantchester to the west, and the woods along Vicar's Brook leading to the city centre. Add to this the fact that when you come north from Trumpington into the city, you end up on the west side of town, so you don't have to spend extra time traversing the city centre in order to get to the colleges. Although many of the houses in locations such as Alpha Terrace are sought after and expensive, Trumpington also contains some more modest, more affordable housing, including the former council houses around Byron Square, site of the village green.
Of course, if I had it to do over again and were not constrained to live in Cambridge, I'd choose north London. This may seem backwards, but the fact is that if you want to meet people and do things, especially if you're a postdoctoral scientist and therefore aren't affiliated with a Cambridge college, Cambridge really hasn't much on offer. Furthermore, if your work is fairly solitary and amenable to telecommuting, you can probably get away with coming to Cambridge just once or twice a week. Fast trains run to Cambridge from King's Cross and Finsbury Park and take just under an hour, buses from Stratford go directly via the M11 and take about an hour, and broadband network connectivity is widely available in London.
LIVING ROUGH
For short-term accommodation, the youth hostel is always an option, though
you'll likely be out of luck unless you reserve at least a day in advance. The
university's accommodation service in Silver Street has listings for short-stay
guest houses and for longer-term accommodation, but they won't give you any
information unless you turn up at their offices in person.
If you're like me, though, you travel light and are just as happy sleeping undisturbed outside as in — especially in the summertime or early autumn when it isn't particularly cold. The best places that I've found to sleep rough in Cambridge are the woods near Byron's Pool between Trumpington and Grantchester, and the woods near Vicar's Brook and Clare fields. Both of these are on the south-west side of Cambridge. Byron's Pool is a bit farther away but offers better potential for secluded bathing; the water is deep enough and the punts never travel farther upriver than the dam just north. To get to Byron's Pool, from Trumpington High Street follow Church Lane to Grantchester Road, and look for the entrance on the left just before you'd be crossing over the Cam, then walk or cycle all the way through the woods to the end of the path, where you have a fenced farm to the left and the Cam to the right.
Vicar's Brook isn't as good for bathing, since the path that runs along it is a pedestrian and cycle route into the city centre and since the brook is shallow and rather muddy. Nevertheless it's possible, and I've done it on summer days when I haven't wanted to take the time to go all the way to Byron's Pool or Addenbrooke's (see below).
If it's too cold for Byron's Pool or Vicar's Brook, don't worry, as there's a free shower at Addenbrooke's Hospital. It's for Addenbrooke's staff, but I've used it many times and nobody's challenged me. To find it, walk in at the main entrance, turn right, turn left immediately as you enter the shops area, then proceed straight out of the shops and towards the wards. To your left, just before you would pass the lifts, there's a door to a stairway. Descend this stairway to the basement, turn right into the corridor, immediately pass through a set of double doors and turn right towards the post room. Continue straight through tunnel junction 30, then turn left at junction 29, where you can't continue straight anymore. At junction 38, opposite the basement entrance, turn left into the corridor that houses the post room, porters' office, and access office. Walk past all of these on the left, and then on the left you'll see two gents toilets next to each other. The shower is in the one that's farther along. If you get lost trying to retrace your steps on the way out, you can exit the building at junction 38 and walk up the drive next to the incinerator.
If you find that you can't get into the shower at Addenbrooke's, or you don't want to go that far from the city centre, you can pay £2.50 for a shower at Kelsey Kerridge sports centre, on Gonville Place on the southeast side of Parker's Piece, just to the right of Parkside swimming pool. These are very nice, clean showers, and they're slightly cheaper than Parkside's.
If you're lucky enough to be affiliated with a college, the college may have a sports facility at which you can shower.