I’m not sure if bench pressing would be possible as wouldn’t I need a spotter?
It depends. There are a few options. Some gyms have what is called a Smith machine which you can use for bench press which has a safety catch inbuilt. It's not entirely a "free weight" because the machine restricts the bar path, but it's not far off. Ask an instructor to demonstrate how the safety catch works.
Alternatively, some standard racks have safety bars which you can set at a height so that if you can't get the bar up, you can drop it onto the bars and it doesnt crush you. It can be annoying as if you dont arch much to meet the bar, the bar can clip the safety bars during your reps, but I guess it's better than death 
Failing that, Dumbbell benchpresses are very effective as (1) it sorts out any strength imbalances between your arms and (2) it's less stable so it's harder work than a bar at the same weight. If you fail the rep you can just bail the DBs sideways.
I don’t know how to start with the dead lifts. I mean I know the technique from body pump but I’m not sure how to put the weights on the bar in the gym.
Get the bar and put it on the floor. A standard bar is 20kg although some gyms have a "ladies' bar" which is 15kg, is narrower and shorter. If you have small hands or you are short, a 15kg bar may work better for grip and stability, but you can load a 15kg bar to same total weight as a 20kg bar so it really is a matter of preference. Once it's on the floor, get the plates and load onto the bar, heaviest first, so if you need a 10kg, a 5kg and a 2.5kg to make the desired weight, put them on in that order. When calcing the weight make sure you remember to add the bar weight. When the plates are loaded, get a collar to secure the weights on either side. Some people dont use collars for deadlifts. I use them for everything as I think it's a good habit but up to you. Best bet is to find a weight you can do for 10 reps with good form, get used to that and then work from there.
Also, a Bodypump deadlift is actually a Romanian deadlift. A full deadlift starts on the floor and is returned to the floor for each rep, with the bar tracking close to your shins.
HTH