The city of Brighton itself isn't that big, but it's merged into neighbouring towns and villages to the east and west; not going too far north due to the protected "green belt" land of the South Downs.
Half of what is referred to as Brighton is in fact a place called Hove (aka "Hove actually"), which is Brighton's more genteel sibling (though becoming a lot livelier now).
The further you go from the centre of Brighton the more suburban everything becomes (with some light industrial units towards the west in Shoreham and beyond).
Sussex University is situated on the outskirts of Brighton near a village called Falmer, on the road towards the town of Lewes.
Google's map of Brighton shows all the main suburbs and I've added the train stations and the 25 bus route (more on which below!). Sussex University is up at Falmer to the north-east of Brighton.
Brighton has a really good bus service, which I thought was a bit pricey until I found out the costs of bus services in other parts of the country. There's more details at the Brighton and Hove Bus website.
Most of the buses run via Churchill Square, which is the main shopping centre in the middle of the town (and straight south from the train station). When it comes to changing buses this will usually be the simplest place to do so, until you get your bearings at least.
To get to the University of Sussex, the bus to take is the 25 (or 25a, 25b or 25c). This is the main university bus service, so it runs through the campus and is definitely the easiest way of getting there.
This bus runs from Portslade (during peak hours) in the west through Hove and Brighton (via Churchill Square) then up the Lewes Road and into the University (there's a big concrete sign saying University of Sussex on the way in, so you'll know when you're there).
As far as I know, there aren't any other regular direct bus services to Sussex University from Brighton, so if you're not staying near the 25's route you'll need to take a bus to either the Old Steine or Churchill Square.
The costs of bus journeys are as follows
The bus service is pretty frequenty (ever 10 or 20 minutes on most routes), and there is a limited night bus service as well (though beware of drunk students if they start looking ill...).
Most of the major roads in Brighton either follow the crests of the hills or the valleys. Roughly speaking these all radiate out from the centre of town, though it gets a good deal more complicated once you're into the one-way system in the middle of town
Anyway, the major ones (going anticlockwise from the east) are
In addition to all of these there is the Brighton by-pass (the A23), which bounds Brighton to the north. The Lewes Road, Ditchling Road, London Road and Dyke Road all intersect with the bypass, though the London Road can get solid with traffic (especially on weekends in Summer).
Sussex University is sited at the place where the Lewes Road and the by-pass merge, so to get to the University you'd either
Brighton has many many traffic wardens (I guess to pay for the bus service), and there isn't any free parking in the middle of town - it'd be best to check with whoever you are staying with for options here, though there is definitely free parking to be found about 20mins walk out from the centre of town.
Sussex university charges for day parking as well, but I'm not sure how much that is (definitely less than 10 quid last time I was there).
Also the speed limit in the UK is 30mph in towns (unless otherwise marked) and there are lots of active speed cameras about (these are usual sign-posted in yellow though). On the motorways the speed limit is 70mph, but most people drive between 65 and 85mph.
If you are looking to hire a car, there are lots of car rental services in and around Brighton, most of which allow booking online. National/Alamo had the cheapest deals last time I looked, but your mileage may vary.
Finally there aren't really any petrol stations in the middle of town - for fuel you'll need to head out of town a bit on the Dyke Road, London Road or Lewes Road or go to one of the big supermarkets on the outskirts of town (there are a few others, but more to say that if you run out of petrol in the town centre you'll have a bit of a walk to get more).
Oh, and don't forget to drive on the left!
There are three train routes out from Brighton station, namely
Unless you're living near one of the stations on the line to Falmer (London Road or Moulescoomb) you will need to travel to Brighton station and change there.
Trains to Falmer run roughly every 15-20 minutes from Brighton, and the majority of them stop off at London Road and Moulescoomb stations on the way. The journey normally takes about 10 minutes, and theres a 5 minute walk the other end.
Preston Park station is the only station still within Brighton on the northerly line, and is a fairly quiet commuter station (trains to Brighton maybe every 20 mins or 1/2 hour).
The westerly coastal line has more stations (Hove, Aldrington, Portslade, Shoreham-by-sea, Southwick and on out at least as far as Worthing). Again trains run along here roughly every 20 minutes.
Trains are a lot more expensive than buses usually too. After 9am you can by a cheap day return (which is usually about 10 or 20p more than the cost of a single fare). I'm not sure what the weekly fares for this are though.
You can catch taxis from several places through Brighton, and
there are taxi ranks at the train station, at Pool Valley (the
coach station), near Western Road and near St. Peter's Church
(amongst others). Usually there are enough travelling around the
streets to flag down.
If you need to call for a cab my current preference is 01273 20 40 60,
as they seem to turn up quicker than others in central Brighton
or Hove.
Travelling by taxi is the most expensive way to get around town
though, usually costing between 5 and 10 quid for the journey
(more at night and on Sundays though).
You could probably cycle up to Falmer on the Lewes Road in about 30 minutes, but on certain days this can be a bit of a wind-tunnel (I wouldn't recommend it if you've not cycled for a while).
There are quite a few cycle lanes too if you're travelling by bike, though the hills and lack of things to lock your bike onto can make it take a bit longer to get from a to b.
There is also a bike rental service down near (the wreck of) the West Pier, that runs during the Summer - not sure if it will be up at Easter though.
Walking to Falmer from Brighton isn't real practical (though possible). However it's really easy to get around the centre of town by foot, as the town centre itself is very compact.