It's safe, but probably not the best if you are putting any kind of real weight on it. You'd be better off looking at Solvent Pipe Weld, but take ID/a parent, you have to be over 18 to buy it - very strong solvent content, and I remember you being fairly young
As per all of the above, in addition you only get one chance at this so you'll have to be quick especially with angled joints. Mark a line on the two pieces of pipework you want to join apply the solvent weld glue to both parts connect where the lines meet now twist the pipe a quarter turn and then twist back again until the marks on the pipes are in-line once again.
ATB
C